Vitamin D deficiency

Reduced serum 25-hydroxyvitamin D below reference values. The US Endocrine Society defines deficiency as 25(OH)D < 20 ng/mL (50 nmol/L) and insufficiency as 20–29 ng/mL. Associated with impaired bone mineralisation, rickets in children, and osteomalacia in adults.

ICD-10 E55.94 drugs

Also known as: Hypovitaminosis D, Vitamin D insufficiency

Drugs used for this condition

ACholecalciferolFirst line · Vitamins. Regulator of calcium-phosphorus metabolismFirst-line therapy for correcting vitamin D deficiency and insufficiency in adults. Standard loading regimens are 50,000 IU weekly for 8 weeks or 6,000 IU daily, followed by maintenance 1,500–2,000 IU daily. Target 25(OH)D is at least 30 ng/mL per the Endocrine Society and Russian clinical guidelines. Doses are 2–3 times higher in obesity, malabsorption syndromes, and in patients on anticonvulsants.
BCalcifediol (25-hydroxyvitamin D)First line · Vitamin D analogue (25-hydroxy metabolite)Used in confirmed vitamin D deficiency (25(OH)D under 20 ng/mL) when fast target response is needed, with hepatic dysfunction or malabsorption. SEEN 2021 and SEEDO 2024 place calcifediol in first-line therapy in Spain. Standard dose 0.266 mg (266 mcg) orally once or twice monthly, or 0.1 mg (100 mcg) weekly depending on baseline. Target 25(OH)D 30–50 ng/mL. In most patients without specific causes, cholecalciferol 800–2000 IU/day suffices; routine calcifediol use without documented deficiency is not indicated.
CCholecalciferol + menaquinone-7 (D3+K2 combo)Add-on therapy · Combined supplement: fat-soluble vitamins D3 and K2D3+K2 combo is marketed to correct vitamin D deficiency with an additional «protective» K2 effect on vascular calcification. In patients with confirmed D deficiency (25(OH)D <20 ng/mL) SEEN 2024 recommends regular cholecalciferol without K2 addition. There is no evidence base for D3+K2 advantage over D3 alone in D deficiency. In warfarin patients the combo is contraindicated: K2 significantly alters INR and requires anticoagulant dose review. If the combo was recommended «to enhance D3», discuss switching to regular cholecalciferol with your doctor.

Marketing claims without evidence base

The drug is promoted for these uses outside international guidelines. Each entry below is analyzed against AEMPS, FDA, EMA, Cochrane and major RCTs.

DCod liver oilNot recommended · Cod liver oil: EPA and DHA combined with retinol (vitamin A) and cholecalciferol (vitamin D3); registered as a medicine in SpainCod liver oil has historically been used as a vitamin D source in confirmed deficiency. Modern endocrinology societies (Endocrine Society 2024, Spanish SEEN 2024) treat 25(OH)D deficiency with pure cholecalciferol at a dose individualised to the blood test – usually 1000–4000 IU/day maintenance or a short course of 50 000 IU/week for 6–8 weeks in severe deficiency. Cod liver oil delivering the same vitamin D dose also provides an extra 1000–1500 mcg of retinol; long-term use can exceed the EFSA adult Tolerable UL (3000 mcg RE/day) when combined with dietary sources (liver, egg yolks, fortified foods) and raises the risk of vitamin A hypervitaminosis. If cod liver oil was bought to treat vitamin D deficiency, discuss with a doctor switching to pure D3, especially for long-term use and risk groups (older adults, pregnant women, women with osteoporosis).

How to read tiers A–F

Evidence tiers belong to the drug-indication pair, not to the drug as a whole: the same substance can be A for one condition and F for another.

AStrong evidence – first or second line in international guidelines
BRecommended in selected cases
CStudy data contradict each other
DBenefit not proven, no documented harm
FDocumented harm, or risk without benefit