{"id":32182,"date":"2026-09-22T11:01:37","date_gmt":"2026-09-22T09:01:37","guid":{"rendered":"https:\/\/test.nefrocenter.it\/low-vitamin-d-why-measure-it-in-the-fall\/"},"modified":"2026-09-22T11:01:37","modified_gmt":"2026-09-22T09:01:37","slug":"low-vitamin-d-why-measure-it-in-the-fall","status":"publish","type":"post","link":"https:\/\/test.nefrocenter.it\/en\/low-vitamin-d-why-measure-it-in-the-fall\/","title":{"rendered":"Low vitamin D: why measure it in the fall"},"content":{"rendered":"

Low vitamin D: symptoms, normal levels and when to supplement. The kidneys activate vitamin D: why deficiency is common in chronic kidney disease. <\/strong><\/p>\n

As fall arrives, the days get shorter, we spend fewer hours outdoors and more and more of our skin stays covered. This is the time of year when people start talking about vitamin D<\/strong> again, often with a seemingly simple question: is it worth measuring?<\/p>\n

The answer needs some clarification. Vitamin D is not a test to be automatically prescribed to the whole population every fall. In healthy people with no risk factors, the main scientific recommendations do not support indiscriminate screening. There are, however, conditions in which knowing the vitamin D level can be clinically useful, and fall is an interesting time especially for those who belong to at-risk groups or need to be monitored over time.<\/p>\n

There is also a lesser-known aspect that makes this topic particularly important for the NefroCenter Group: vitamin D and the kidneys are closely linked<\/strong>.<\/p>\n

We often think of the kidneys as two organs whose only job is to filter the blood and produce urine. In reality they perform much more complex functions. They help control blood pressure, regulate water and electrolytes, take part in acid-base balance, produce erythropoietin and play a decisive role in vitamin D metabolism. It is mainly in the kidney, in fact, that one of the transformations needed to obtain the biologically active form of the vitamin takes place.<\/p>\n

This helps explain why, in people with chronic kidney disease (CKD)<\/strong>, the issue is not only how much vitamin D is taken in or produced through sun exposure. As kidney impairment progresses, the complex balances involving vitamin D, calcium, phosphorus and parathyroid hormone can also change.<\/p>\n

It is not correct to say that all<\/em> patients with CKD necessarily have a vitamin D deficiency. It is, however, a frequent and clinically relevant condition, which must be assessed within the broader mineral and bone metabolism of kidney disease.<\/p>\n

What vitamin D really is<\/h2>\n

We call it a vitamin, but vitamin D has particular characteristics compared with many other vitamins. Part of it can be taken in through food, but a significant share is produced by the body through the action of ultraviolet rays on the skin.<\/p>\n

The vitamin D obtained through the sun, food or supplements, however, is not yet biologically active<\/strong>.<\/p>\n

It has to go through two transformations.<\/p>\n

The first takes place mainly in the liver, where it is converted into 25-hydroxyvitamin D [25(OH)D]<\/strong>, also called calcidiol. This is the form that is generally measured with a blood test when we want to know a person’s vitamin D status.<\/p>\n

The second transformation takes place mainly in the kidneys<\/strong>, which convert 25(OH)D into the active form 1,25-dihydroxyvitamin D [1,25(OH)\u2082D]<\/strong>, or calcitriol.<\/p>\n

It is a fundamental step.<\/p>\n

The kidney, therefore, is not simply an organ that eliminates what the body does not need: it takes part in the transformation of a substance that is essential for the body’s mineral homeostasis.<\/p>\n

Vitamin D is best known for its role in skeletal health. It promotes the absorption of calcium in the intestine and, together with other hormones and minerals, helps maintain the balance needed for bones and muscles.<\/p>\n

Its biological activity, however, is not limited to the skeleton. Vitamin D receptors are present in many tissues and its metabolism interacts with numerous systems. This does not mean, as is sometimes claimed online, that taking high doses of vitamin D can prevent or treat a long list of diseases indiscriminately.<\/p>\n

There is an important difference between biological role<\/strong>, associations observed in studies and demonstrated benefits of supplementation.<\/p>\n

And it is a fundamental distinction, to avoid turning an essential vitamin into a sort of universal remedy.<\/p>\n

Why is so much said about low vitamin D in the fall?<\/h2>\n

The link with the seasons comes mainly from its production in the skin.<\/p>\n

When the skin receives an adequate amount of UVB radiation, the body can synthesize vitamin D. The ability to do so, however, depends on many factors: season, latitude, time of day, age, skin pigmentation, how much of the body is exposed, clothing, lifestyle habits and time spent outdoors.<\/p>\n

In the fall, first of all, our behavior changes.<\/p>\n

The days gradually get shorter, temperatures drop and we generally spend less time outdoors. Clothing also leaves less skin exposed than in the summer months.<\/p>\n

Fall can, however, become a good reminder to reassess your individual risk<\/strong>.<\/p>\n

An older person who rarely leaves the house does not have the same profile as a healthy young adult. A patient with osteoporosis does not have the same needs as someone with no risk factors. And above all, a patient with chronic kidney disease requires a completely different reading of vitamin D metabolism.<\/p>\n

Medicine, once again, works best when it avoids automatic routines.<\/p>\n

Low vitamin D: what are the symptoms?<\/h2>\n

One of the most frequent Google searches is \u201clow vitamin D symptoms\u201d<\/strong>. The problem is that the answer is not as straightforward as it might seem.<\/p>\n

A drop in vitamin D can in fact be asymptomatic<\/strong>, especially when it is not severe.<\/p>\n

When the deficiency becomes significant, signs such as tiredness, muscle weakness, and muscle or bone pain may appear. In severe cases that persist over time, impaired bone mineralization can contribute to osteomalacia in adults.<\/p>\n

Among the signs that may be considered in the context of hypovitaminosis D are fatigue, muscle aches, widespread or localized pain and frequent unexplained falls<\/strong>, to be interpreted, of course, within the overall clinical picture.<\/p>\n

The most important point is another: these complaints are extremely nonspecific.<\/p>\n

Feeling tired in October does not automatically mean having too little vitamin D. Muscle pain, weakness or fatigue can have dozens of different causes, from anemia to thyroid disorders, from infections to sleep problems, and even the effects of certain medications.<\/p>\n

For this reason, a symptom cannot replace a medical evaluation or, when truly indicated, a blood test.<\/p>\n

Likewise, a low value discovered by chance does not necessarily explain all the complaints reported by the person.<\/p>\n

Which vitamin D is measured in blood tests?<\/h2>\n

When the doctor wants to assess vitamin D status, the reference test is generally 25-hydroxyvitamin D<\/strong>, shown on the report as: 25(OH)D <\/strong>or 25-OH vitamin D<\/strong>.<\/p>\n

It is important to know this abbreviation because the active form, 1,25(OH)\u2082D<\/strong>, also exists, but the latter is not normally the best test for establishing the body’s vitamin reserves.<\/p>\n

25(OH)D reflects both the vitamin D produced by the skin and the vitamin D that comes from food and any supplements. The active form, by contrast, has a much shorter circulating life and is tightly regulated by mechanisms involving, among others, parathyroid hormone, calcium and phosphorus. For this reason it may not drop until the deficiency is significant.<\/p>\n

It is a particularly interesting detail in nephrology, where the problem can involve both the availability of vitamin D and the body’s ability to handle its metabolism correctly.<\/p>\n

What are the normal values?<\/h2>\n

This is probably the most searched question and also the one on which it is easiest to find contradictory information online.<\/p>\n

There is, in fact, no single universally recognized number that is the \u201cperfect value\u201d<\/strong> for every person and every clinical condition.<\/p>\n

The general reference is:<\/p>\n

\n
\n
\n\n\n\n\n\n\n\n\n
25(OH)D in the blood<\/th>\nGeneral interpretation<\/th>\n<\/tr>\n<\/thead>\n
<12 ng\/mL<\/strong><\/td>\nassociated with vitamin D deficiency<\/td>\n<\/tr>\n
12\u2013<20 ng\/mL<\/strong><\/td>\ngenerally considered inadequate<\/td>\n<\/tr>\n
\u226520 ng\/mL<\/strong><\/td>\ngenerally adequate for most people<\/td>\n<\/tr>\n
>50 ng\/mL<\/strong><\/td>\nmay be associated with potential adverse effects<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n<\/div>\n<\/div>\n

Values can also be expressed in nmol\/L<\/strong>: 1 ng\/mL equals 2.5 nmol\/L.<\/p>\n

But this table should not become a tool for self-diagnosis.<\/p>\n

The scientific literature itself stresses that no \u201coptimal\u201d 25(OH)D level has been defined that applies equally to bone health and general health. In addition, there may be differences between laboratory methods and between clinical recommendations used in different settings.<\/p>\n

It is therefore possible that a person will find slightly different ranges or indications on their own report.<\/p>\n

The result should be interpreted by considering age, clinical conditions, bone health, kidney function, treatments, any pregnancy and other individual factors. A number, on its own, does not tell the whole story.<\/p>\n

Vitamin D below 20, below 12 or below 10: when should you worry?<\/h2>\n

It is around the thresholds that much of the confusion arises.<\/p>\n

According to the reference values, below 12 ng\/mL<\/strong> the risk of true deficiency increases, while between 12 and 20 ng\/mL the value is generally considered inadequate for bone and general health in healthy people. Values equal to or above 20 ng\/mL are considered adequate for most of the population.<\/p>\n

In Italy, the Italian Medicines Agency (AIFA) indicates a threshold of about 10-12 ng\/mL<\/strong> in healthy asymptomatic people for considering starting treatment, while reiterating that indiscriminate testing is not appropriate in these people.<\/p>\n

Does this mean that anyone with a level of 19 ng\/mL should immediately buy a supplement?<\/p>\n

No.<\/p>\n

The decision depends on the context.<\/p>\n

A laboratory value must be read together with the reason the test was requested, the presence of symptoms, coexisting diseases, bone health, fracture risk, intestinal absorption, treatments and, especially in the context of kidney disease, kidney function<\/strong>.<\/p>\n

Kidneys and vitamin D: the link many people do not know about<\/h2>\n

To truly understand vitamin D, we have to go back to the kidneys.<\/p>\n

After being produced in the skin or taken into the body, vitamin D undergoes its first transformation in the liver and becomes 25(OH)D. It then reaches the kidney, where an enzyme makes it possible to produce the active form, calcitriol.<\/p>\n

It is through this metabolic network that vitamin D takes part in regulating the intestinal absorption of calcium and in maintaining mineral balance.<\/p>\n

The kidney therefore sits at the center of a system in which vitamin D, calcium, phosphorus and parathyroid hormone (PTH)<\/strong> interact.<\/p>\n

When kidney function decreases significantly, this balance can progressively become disrupted.<\/p>\n

The NefroCenter website, in its section dedicated to nephrology, points out that the endocrine functions of the kidneys include the production of the active form of vitamin D, and that in people with kidney failure, changes in calcium-phosphorus metabolism and in the bone can appear.<\/p>\n

This is one of the reasons why vitamin D and chronic kidney disease<\/strong> must be considered together.<\/p>\n

Vitamin D and chronic kidney disease: why deficiency is common<\/h2>\n

The relationship between chronic kidney disease and vitamin D<\/strong> cannot be reduced to sun exposure alone.<\/p>\n

As CKD progresses, the body can develop a series of alterations in mineral metabolism. The kidney’s ability to produce calcitriol may decline and, at the same time, phosphorus, calcium and PTH may change.<\/p>\n

To this can be added other factors that favor low 25(OH)D levels in some patients: advanced age, reduced sun exposure, diet, general condition, obesity, urinary protein loss in some kidney diseases and other clinical situations.<\/p>\n

The result is a picture far more complex than simply \u201clow vitamin D\u201d.<\/p>\n

In nephrology, in fact, we speak of CKD-MBD<\/strong>, that is, Chronic Kidney Disease-Mineral and Bone Disorder<\/em>: the set of mineral and bone abnormalities associated with chronic kidney disease.<\/p>\n

Vitamin D, calcium, phosphorus and PTH thus become pieces of the same mosaic.<\/p>\n

The recent report from Kidney Disease: Improving Global Outcomes (KDIGO) on the mineral and bone disorders of CKD stresses the need to interpret PTH in relation to calcium, phosphorus and 25(OH)D as well, and points out that important scientific questions remain open about the optimal vitamin D targets in patients with CKD.<\/p>\n

It is an important point from a communication standpoint too: saying that in CKD vitamin D is \u201calmost always deficient\u201d conveys how common the problem is, but scientifically it is preferable to speak of frequent deficiency or insufficiency<\/strong>, not an inevitable one.<\/p>\n

Every patient must be evaluated individually.<\/p>\n

Parathyroid hormone: why it can rise when the kidneys work less well<\/h2>\n

Here another protagonist enters the scene, one that patients often do not know: PTH, or parathyroid hormone<\/strong>.<\/p>\n

The parathyroid glands are small glands that help regulate calcium. When, in chronic kidney disease, the balance of calcium, phosphorus and vitamin D changes, the production of PTH can increase.<\/p>\n

Over time, so-called secondary hyperparathyroidism<\/strong> can develop.<\/p>\n

It is one of the reasons why, in a patient with kidney disease, it is not enough to look only at the vitamin D value. The nephrologist may need to read several parameters at the same time to understand mineral and bone metabolism.<\/p>\n

The evaluation may include, depending on the stage of the disease and the clinical picture, calcium, phosphorus, PTH, alkaline phosphatase and 25(OH)D<\/strong>, in addition, of course, to the tests that describe kidney function.<\/p>\n

The meaning of a vitamin D value of 15 ng\/mL, therefore, is not necessarily the same in a healthy adult and in a person with advanced CKD and abnormalities of PTH, calcium and phosphorus.<\/p>\n

Low vitamin D and the kidneys: which tests to check?<\/h2>\n

If chronic kidney disease exists, or there is a suspected kidney problem, vitamin D is only one part of the evaluation.<\/p>\n

To assess how well the kidneys work, parameters such as creatinine and eGFR<\/strong> are used, while a urine test and the measurement of albuminuria can provide information on the presence of kidney damage. The NefroCenter pathway dedicated to kidney function tests includes both blood and urine tests, whose interpretation must be integrated with the clinical history and risk factors.<\/p>\n

To learn more: Kidney function tests \u2013 NefroCenter<\/a>.<\/p>\n

When the doctor considers it necessary to study mineral metabolism as well, the appropriate tests can be added.<\/p>\n

The logic is important: we do not treat an isolated number, we treat a person<\/strong>.<\/p>\n

Who should have the level checked?<\/h2>\n

There is no recommendation that every adult must necessarily check their vitamin D once a year.<\/p>\n

Testing can take on greater significance when there are conditions that increase the risk of deficiency or when knowing the result can concretely change clinical management.<\/p>\n

Situations to discuss with the doctor may include osteoporosis and bone fragility, malabsorption conditions, certain treatments, reduced sun exposure, particular clinical conditions and, of course, chronic kidney disease<\/strong>.<\/p>\n

In patients with kidney disease, the decision on how often to test depends on the stage of the disease, on the abnormalities already present and on the treatments under way.<\/p>\n

The KDIGO recommendations on CKD mineral and bone disorder in fact provide that measuring 25(OH)D may be considered and that repeating the test should be determined on the basis of the baseline value and of therapeutic interventions.<\/p>\n

It does not mean, therefore, \u201cvitamin D every October for everyone\u201d.<\/p>\n

It means testing when there is a clinical reason to do so<\/strong>.<\/p>\n

When to supplement vitamin D?<\/h2>\n

The second big question is: when should you take vitamin D?<\/strong><\/p>\n

The safest answer is: when there is an appropriate indication, with the dose and method set on the basis of the individual situation.<\/p>\n

Supplementation should not be decided solely by looking at a number found on a report and comparing it with an online table.<\/p>\n

AIFA identifies specific conditions in which drug supplementation may be indicated and distinguishes the cases in which the decision depends on the 25(OH)D level. In healthy asymptomatic people, the Agency sets the threshold for starting treatment at around 10-12 ng\/mL, while there are clinical categories for which the recommendations are different.<\/p>\n

In other words, having low values does not automatically mean the same treatment for everyone<\/strong>.<\/p>\n

The dose, the duration, the formulation and the need for monitoring all change.<\/p>\n

And in patients with kidney failure this caution becomes even more important.<\/p>\n

Vitamin D and kidney failure: why you should not go it alone<\/h2>\n

A person might reason like this: \u201cMy kidneys activate less vitamin D, so I will take more.\u201d<\/p>\n

This is exactly the kind of oversimplification to avoid.<\/p>\n

In chronic kidney disease, the problem can involve at the same time the availability of the vitamin, its activation, calcium, phosphorus and PTH. In addition, there are substantial differences between so-called nutritional vitamin D<\/strong> and the active forms or analogs used in specific nephrology settings.<\/p>\n

They are not interchangeable products to be chosen on your own.<\/p>\n

The management of secondary hyperparathyroidism and of the mineral abnormalities of CKD requires a nephrology evaluation, especially in the more advanced stages.<\/p>\n

KDIGO guidelines and documents in fact continue to stress the need to personalize the management of mineral and bone metabolism in chronic kidney disease.<\/p>\n

The goal is not simply to \u201craise vitamin D\u201d.<\/p>\n

It is to maintain a metabolic balance that is compatible with the patient’s clinical situation.<\/p>\n

More vitamin D means feeling better? Not necessarily<\/h2>\n

In supplement culture there is often the idea that if a substance is useful, having more of it is even better.<\/p>\n

With vitamin D, this reasoning is wrong.<\/p>\n

It is a fat-soluble vitamin, and excessive intake through supplements can cause toxicity, in particular through an excessive rise in blood calcium. The National Institutes of Health (NIH) points out that serum 25(OH)D concentrations above 50 ng\/mL<\/strong> may be associated with potential adverse effects, especially when levels rise further.<\/p>\n

The problem does not normally come from sun exposure, because the body has mechanisms that limit excessive production in the skin. The risk mainly concerns the inappropriate intake of high doses of supplements.<\/p>\n

In patients with kidney disease, moreover, calcium and phosphorus are already elements that require particular attention.<\/p>\n

For this reason \u201cdo-it-yourself\u201d supplementation, perhaps by adding up several products that contain vitamin D, is not a good strategy.<\/p>\n

Sun and vitamin D: how much exposure do you need?<\/h2>\n

Here we must avoid another common myth: there is no universal number of minutes in the sun that can guarantee vitamin D for everyone.<\/p>\n

Skin synthesis varies enormously depending on season, latitude, time of day, skin pigmentation, age, clothing and the amount of skin exposed.<\/p>\n

It would therefore not be scientifically correct to prescribe online \u201c15 minutes of sun a day\u201d as if it were a drug dose.<\/p>\n

Protecting the skin from the damage of ultraviolet radiation also remains an important goal. It is not advisable to seek vitamin D through excessive exposure or sunburn.<\/p>\n

The balance between skin health and vitamin D metabolism should be approached with common sense and, in people at risk of deficiency, through a clinical evaluation rather than by indiscriminately increasing sun exposure.<\/p>\n

Which foods contain vitamin D?<\/h2>\n

Diet contributes to vitamin D intake, although relatively few foods contain naturally significant amounts.<\/p>\n

Food sources include mainly some fatty fish<\/strong>, while smaller amounts may be present in egg yolk and other foods. There are also fortified products, whose availability varies between countries and commercial types.<\/p>\n

A balanced diet remains fundamental, but in a clinically significant deficiency it is not always realistic to think of correcting the problem simply by eating more of a single food.<\/p>\n

And in patients with chronic kidney disease, a further variable appears.<\/p>\n

Foods are not chosen only on the basis of vitamin D. In the advanced stages of CKD, personalized guidance may be needed regarding, for example, phosphorus, potassium, protein and other nutrients.<\/p>\n

The \u201cvitamin D diet\u201d therefore cannot replace an individual nutritional and nephrology evaluation.<\/p>\n

Fall tiredness: is it really the fault of vitamin D?<\/h2>\n

It is an understandable question.<\/p>\n

September and October coincide with the return to routine, fewer hours of daylight, new work and study rhythms and changes in sleep habits. Many people report feeling more tired and look for an explanation in their vitamin levels.<\/p>\n

A significant vitamin D deficiency can be associated with fatigue and muscle problems, but tiredness alone does not allow a deficiency to be diagnosed<\/strong>.<\/p>\n

Before attributing it to vitamin D, the overall picture must be considered.<\/p>\n

Anemia, thyroid disorders, metabolic changes, sleep problems, infections, stress, medications and numerous other conditions can produce similar symptoms.<\/p>\n

This is even more true in patients with chronic kidney disease, in whom fatigue can have multiple explanations and requires a broader evaluation.<\/p>\n

Vitamin D, bones and muscles: why the problem is not only for older people<\/h2>\n

Vitamin D is often associated with older age because osteoporosis, frailty and the risk of falling become more relevant with aging.<\/p>\n

But bone metabolism is a process that accompanies us throughout life.<\/p>\n

A severe and prolonged deficiency can compromise the proper mineralization of the skeleton. In adults it can contribute to osteomalacia, a condition different from osteoporosis but just as important.<\/p>\n

In older people, moreover, the problem often fits into a more complex picture in which reduced muscle mass, lower physical activity, less sun exposure, multiple treatments and chronic diseases may coexist.<\/p>\n

If a reduction in kidney function is added to this, the evaluation of mineral metabolism takes on even greater significance.<\/p>\n

Vitamin D and dialysis<\/h2>\n

In dialysis patients, the relationship between kidney, vitamin D, calcium, phosphorus and parathyroid hormone becomes particularly delicate.<\/p>\n

When kidney function is severely impaired, the body loses an important part of its physiological ability to regulate this system. Complex abnormalities of mineral and bone metabolism can therefore develop.<\/p>\n

For this reason, in dialysis centers vitamin D is not simply viewed as a supplement to be taken periodically.<\/p>\n

The patient is followed through tests and checks that allow the nephrologist to assess the overall balance and decide on any treatments based on how the parameters change.<\/p>\n

Calcium, phosphorus and PTH take on central importance, and treatment decisions are adapted to the person.<\/p>\n

It is one of the clearest examples of how modern nephrology goes far beyond the kidney’s filtering function alone.<\/p>\n

Why vitamin D tells us something important about our kidneys<\/h2>\n

The metabolism of vitamin D offers a good opportunity to understand how complex the kidneys are as organs.<\/p>\n

Filtering the blood is only one part of their work.<\/p>\n

The kidneys take part in regulating blood pressure, the balance of water and electrolytes, the production of erythropoietin and the activation of vitamin D. NefroCenter Group<\/a><\/p>\n

When kidney function decreases, the consequences can therefore appear in systems that seem far removed from the urine.<\/p>\n

This is also why chronic kidney disease can be silent in its early stages<\/strong>, yet have systemic consequences over time.<\/p>\n

The NefroCenter website also offers an in-depth article on chronic kidney disease, its stages and the tests used to diagnose and monitor it.<\/p>\n

Chronic kidney disease: symptoms, stages and diagnosis<\/a><\/p>\n

When to see a nephrologist<\/h2>\n

Having low vitamin D does not automatically mean having kidney disease.<\/p>\n

It is important to say this clearly.<\/p>\n

Vitamin D deficiency is also common in people who have no kidney disease at all. A single low value therefore cannot be used as a \u201ctest\u201d to diagnose a kidney problem.<\/p>\n

A nephrology evaluation becomes particularly important, instead, when changes in kidney function are already present, as well as albuminuria or proteinuria, diabetes, hypertension, known CKD or persistent changes in parameters such as creatinine and eGFR.<\/p>\n

In these patients, vitamin D can become one of the elements of a broader metabolic picture.<\/p>\n

The NefroCenter Group devotes its specialist activity to the prevention, diagnosis and treatment of acute and chronic kidney diseases and to the management of their complications, including abnormalities of mineral and bone metabolism.<\/p>\n

Vitamin D in the fall: so, should you get tested or not?<\/h2>\n

We can now return to the initial question.<\/p>\n

Fall does not make vitamin D testing mandatory.<\/strong><\/p>\n

For a healthy person with no symptoms and no particular risk factors, there is no general recommendation to have 25(OH)D tested every year simply because October has arrived.<\/p>\n

The discussion changes when there is a clinical reason.<\/p>\n

Fall can be a useful time to take stock with your doctor, especially if there are previous low values, conditions that increase the risk of deficiency, bone problems, reduced sun exposure, particular treatments or chronic kidney disease<\/strong>.<\/p>\n

In the latter case, however, the test should not be interpreted in isolation.<\/p>\n

The question is not only:<\/p>\n

\u201cHow high is my vitamin D?\u201d<\/strong><\/p>\n

but rather:<\/p>\n

\u201cHow is my mineral metabolism working in the context of my kidney function?\u201d<\/strong><\/p>\n

It is an apparently small difference, but it completely changes the perspective.<\/p>\n

Frequently asked questions about vitamin D<\/h1>\n

What is the normal vitamin D level?<\/h3>\n

25(OH)D is the main parameter used to assess vitamin D status. According to the NIH\/NASEM references, values equal to or above 20 ng\/mL are generally considered adequate for most people, between 12 and less than 20 ng\/mL may be inadequate, and below 12 ng\/mL the risk of deficiency increases. The result must in any case be interpreted clinically.<\/p>\n

What are the symptoms of low levels?<\/h3>\n

A deficiency may cause no symptoms at all. In more severe cases, tiredness, weakness, or muscle and bone pain may appear. These symptoms are nonspecific, however, and cannot on their own diagnose a deficiency.<\/p>\n

Which test is needed to check it?<\/h3>\n

The test normally used is the blood measurement of 25-hydroxyvitamin D, or 25(OH)D<\/strong>. The active form, 1,25(OH)\u2082D, is not normally used to assess general vitamin reserves.<\/p>\n

Why are the kidneys important for vitamin D?<\/h3>\n

After a first transformation in the liver, vitamin D is converted mainly in the kidneys into its biologically active form, calcitriol. For this reason, a significant impairment of kidney function can interfere with vitamin D metabolism.<\/p>\n

Do people with kidney failure always have low vitamin D?<\/h3>\n

No. Deficiency and insufficiency are common in people with chronic kidney disease, but they are not inevitable in every patient. In addition, in CKD it is necessary to consider not only 25(OH)D but the entire balance that includes calcium, phosphorus and PTH.<\/p>\n

Does low vitamin D mean the kidneys are not working?<\/h3>\n

No. There are numerous causes of low vitamin D, and a reduced value does not allow a kidney disease to be diagnosed. To study kidney function, specific tests are used, including creatinine, eGFR, a urine test and albuminuria when indicated.<\/p>\n

When should vitamin D be supplemented?<\/h3>\n

The decision depends on the level, the presence of symptoms, risk factors and clinical conditions. AIFA<\/a> indicates specific situations in which treatment is appropriate and, in healthy asymptomatic people, sets the threshold for starting treatment at around 10-12 ng\/mL. Supplementation must in any case be evaluated by the doctor.<\/p>\n

Can someone with kidney disease take it?<\/h3>\n

It may be indicated, but the type of vitamin D, the dose and the monitoring must be set by the doctor or nephrologist<\/strong>. In advanced CKD, mineral metabolism is complex and self-supplementation is not appropriate.<\/p>\n

Should it be checked every fall?<\/h3>\n

Not necessarily. Routine screening in healthy people without specific indications is not recommended. In the presence of risk factors or conditions such as CKD, the doctor may instead schedule the test and decide when to repeat it.<\/p>\n

Vitamin D and the kidneys: prevention starts with knowledge<\/h2>\n

Vitamin D is an excellent example of how our body works through relationships rather than separate compartments.<\/p>\n

The sun contributes to its production. The liver starts the transformation. The kidney takes part in its activation.<\/strong> The intestine, bones, parathyroid glands and mineral metabolism then enter into a finely regulated balance.<\/p>\n

When the kidneys work less well, this balance can change.<\/p>\n

For this reason, especially in people with chronic kidney disease, talking about vitamin D also means talking about calcium, phosphorus, parathyroid hormone, bone health and kidney function<\/strong>.<\/p>\n

Fall can be a good time to remember this, but it should not turn into the season of tests and supplements taken automatically.<\/p>\n

True prevention consists of understanding who needs to be checked, which tests are needed and how to interpret them together<\/strong>.<\/p>\n

And this is where personalized medicine makes the difference: not chasing a number on the report, but understanding its meaning in the person’s clinical history.<\/p>\n","protected":false},"excerpt":{"rendered":"

Low vitamin D: symptoms, normal levels and when to supplement. The kidneys activate vitamin D: why deficiency is common in chronic kidney disease. As fall arrives, the days get shorter, we spend fewer hours outdoors and more and more of our skin stays covered. This is the time of year when people start talking about […]<\/p>\n","protected":false},"author":8,"featured_media":31213,"comment_status":"","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[1325],"tags":[],"area_medica":[1386,1373],"voce_indice":[],"class_list":["post-32182","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-news","area_medica-endocrinology","area_medica-nephrology"],"acf":[],"yoast_head":"\nLow vitamin D: why measure it in the fall - Gruppo NefroCenter<\/title>\n<meta name=\"description\" content=\"Low vitamin D: symptoms, levels and when to supplement. 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