Vitamin D deficiency is one of the most common findings on routine blood tests in Israel, despite the sunshine. The vitamin, which is in fact a hormone the body makes in the skin on exposure to sunlight, is responsible for absorbing calcium from the gut and building normal bone, and it also affects muscle strength and stability. In most people the deficiency is mild, causes no symptoms and is corrected with a simple supplement. But when the deficiency is deep or keeps returning despite treatment, when it comes with bone pain, muscle weakness or a fracture from a minor fall, or when there is reason to think that absorption, the kidneys or other glands are involved, it justifies a work-up with an endocrinologist as part of a broader assessment of bone health.
What vitamin D does in the body
The vitamin is made in the skin from exposure to sunlight, and to a smaller extent comes from food: oily fish, egg yolk and fortified foods. In the liver and the kidneys it goes through two processing steps until it becomes an active hormone. The active hormone increases the absorption of calcium and phosphate from the gut and allows them to be built into bone. When vitamin D is lacking, the body absorbs less calcium, the parathyroid glands increase their activity to keep the blood calcium level normal, and they do this by drawing calcium out of bone. Over time the bone weakens even when the blood calcium level looks normal.
The vitamin also acts on muscle: a deep deficiency causes weakness in the muscles of the thighs and shoulders, difficulty getting up from a chair and climbing stairs, and in older people a tendency to fall, which is the main cause of fractures.
Who is at risk of deficiency
- People who spend most of the day indoors at home or in the office, or who dress in covering clothing.
- People who use sunscreen consistently, which also blocks the production of the vitamin in the skin.
- People with dark skin, which produces less of the vitamin from the same exposure.
- People with excess body mass, in whom the vitamin is stored in fat tissue and is less available.
- Adults over the age of sixty-five, whose skin produces less.
- Pregnant and breastfeeding women, and breastfed babies.
- People with malabsorption conditions such as celiac disease or Crohn’s disease, or after weight-loss surgery.
- People living with kidney or liver disease, or taking certain medicines, including anticonvulsants and long-term steroids.
What vitamin D deficiency feels like
A mild to moderate deficiency is not felt at all and is discovered on a blood test. A deep, prolonged deficiency may show up as tiredness, dull bone pain, mainly in the lower back, pelvis and thighs, muscle weakness, cramps and low mood. In children a severe deficiency causes rickets, and in adults a softening of the bone called osteomalacia, in which bone is built without enough minerals and becomes painful and weak.
It is important to know that these symptoms are not specific, and many of them come from other causes. A vitamin D supplement is therefore no substitute for a work-up of prolonged tiredness or pain, even when the blood level is low. If the symptoms persist after the level has returned to a sufficient range, the cause should be sought elsewhere rather than by raising the dose of the supplement.
What the blood test result means
The standard test measures the storage form of the vitamin in the blood. The result falls into three ranges: deficiency, a borderline level and a sufficient level, and the exact cut-offs vary slightly between laboratories and guidelines. There is no proven benefit in particularly high levels, and a prolonged excess from very high-dose supplements can cause high calcium levels and kidney stones. The goal is therefore a sufficient range, not “as much as possible”.
When the level is low, the doctor usually also checks calcium, phosphate, kidney function and sometimes the parathyroid hormone. A combination of low vitamin D with high calcium, or with a high parathyroid hormone that does not fall after the deficiency is corrected, is the sign that moves the work-up to an endocrinologist.
When to see an endocrinologist
In most cases the family doctor treats vitamin D deficiency. It is worth booking a visit with a private endocrinologist in Modi’in in these situations:
- A deep deficiency that does not improve, or keeps returning, despite a supplement at a suitable dose taken consistently.
- Deficiency together with an abnormal blood calcium level, high or low.
- A high parathyroid hormone that stays high even after the deficiency is corrected.
- A fracture caused by a fall from standing height or a minor injury, at any age.
- Persistent bone pain or muscle weakness that makes it hard to stand up and climb stairs.
- Osteoporosis diagnosed on a bone density test, especially in men or in women before the menopause.
- A malabsorption condition, kidney or liver disease, or long-term steroid treatment.
- A loss of more than three centimetres in height or a stoop of the upper back.
- A family history of hip fractures or early osteoporosis.
What the endocrinologist checks
The visit begins with a conversation: results of previous tests, supplements and medicines, sun exposure and eating habits, other conditions, past fractures, menstrual status in women and family history. The doctor checks height and posture, muscle strength and stability, and looks for signs of diseases that affect bone.
As needed, the doctor refers you for broader blood tests, including kidney and liver function, parathyroid hormone, markers of bone formation and breakdown, thyroid function, sex hormones and markers for celiac disease. When damage to the bone is suspected, the doctor refers you for a bone density test and spine X-rays as needed. The purpose of the work-up is to answer two questions: why the vitamin is low, and whether the bone has already been affected.
How the deficiency and the bone are treated
The basic treatment is a vitamin D supplement, at a daily or weekly dose the doctor sets according to the depth of the deficiency, body mass and other conditions. In a deep deficiency a loading dose is given first, followed by a long-term maintenance dose, because the deficiency tends to return when the supplement stops. A repeat blood test is usually done after three months. In malabsorption or kidney disease, special forms of the vitamin or higher doses under close follow-up may be needed.
Alongside the supplement, adequate calcium from food and, if necessary, from a supplement matters, as do weight-bearing exercise such as walking and muscle strengthening, stopping smoking and limiting alcohol. When osteoporosis has been diagnosed, vitamin D and calcium are only the foundation, and the doctor tailors dedicated medication that strengthens bone and reduces the risk of fractures, and follows its effectiveness over years.
Why a supplement alone is not always enough
Low vitamin D is sometimes the visible tip of a wider problem: an overactive parathyroid gland, an undiagnosed malabsorption condition, or osteoporosis progressing quietly until the first fracture. An orderly work-up in the right cases identifies the cause, prevents fractures and treats the bone before irreversible damage is done. If a fall has already happened, read our article on a first fall in an older adult.
At EliteMed in the Ayala 360 complex in Modi’in you can book a visit with a specialist endocrinologist without a referral, and the consultation can be held in English. The information here is general and does not replace an examination and advice from a doctor.
Frequently asked questions
Why is vitamin D deficiency common in Israel, a sunny country?
Because most people spend the daylight hours indoors, dress in covering clothing or use sunscreen, all of which reduce the production of the vitamin in the skin. Dark skin, older age and excess body mass also reduce production and availability. The deficiency is therefore common in hot countries too.
Can I take vitamin D without a blood test?
A supplement at a moderate daily dose is considered safe for most healthy people, but it is worth checking the level before starting a high dose, and repeating the test after a few months. Very high doses over time can cause excess calcium and kidney stones, so they should not be taken without a doctor’s follow-up.
How long does it take to correct a vitamin D deficiency?
With a suitable dose the blood level usually rises to a sufficient range within three months, and then a maintenance dose follows. The improvement in muscle strength and bone pain, when they stem from the deficiency, is felt over several months. The bone itself strengthens more slowly, so persistence matters.
Does low vitamin D mean I have osteoporosis?
No. Vitamin D deficiency is a risk factor for weak bone, but osteoporosis is diagnosed only on a bone density test or after a typical fracture. Someone with a deficiency together with other risk factors, such as early menopause, steroid treatment, a previous fracture or a family history, is referred for a bone density test at the doctor’s discretion.
When is a family doctor enough and when do I need an endocrinologist?
A mild to moderate deficiency in a healthy person is well managed by the family doctor with a supplement and a repeat test. An endocrinologist is needed when the deficiency is deep or returns despite treatment, when there is a disturbance in calcium levels or parathyroid hormone, after a fracture from a minor fall, when there is a malabsorption or kidney condition, or when osteoporosis has been diagnosed and needs treatment and follow-up.