Vitamin D Deficiency and Its Metabolic Effects

Impact of vitamin D insufficiency on bone health and overall systemic wellbeing.

Written by: Saygı Hospital Health Guide Editorial Board

Last updated: June 11, 2026

This content has been compiled by the Saygı Hospital Health Guide Editorial Board and is periodically reviewed by a specialist physician.

References (5)

This content is for informational purposes only and does not constitute medical advice. You can book an appointment at our Dahiliye (İç Hastalıkları) department. Book Appointment →

What is Vitamin D Deficiency and Its Metabolic Effects?

Vitamin D (cholecalciferol) is a hormone synthesised in the skin via sunlight and converted to its active form by the liver and kidneys. A 25-OH vitamin D level below 20 ng/mL is defined as deficiency, while 20-30 ng/mL represents insufficiency.

Vitamin D deficiency adversely affects not only bone-mineral metabolism but also immune function, muscle performance and cardiovascular health. Covered clothing, inadequate sun exposure, dark skin pigmentation and obesity are leading risk factors.

Severe deficiency causes rickets in children and osteomalacia (bone softening) in adults. Chronic deficiency increases osteoporosis risk and elevates rates of falls and fractures.

Symptoms

Bone pain and muscle weakness

Fatigue and lassitude

Frequent infections

Depressed mood

Hair loss

Delayed wound healing

Risk Factors

Inadequate sun exposure

Dark skin pigmentation

Obesity

Advanced age

Malabsorption syndromes (celiac, Crohn)

Chronic kidney or liver disease

When to See a Doctor?

If you experience any of the following symptoms, seek medical attention promptly:

Widespread bone pain and muscle weakness
History of recurrent falls or fractures
Screening for at-risk individuals (elderly, covered clothing, obese)
Lack of improvement despite treatment in known deficiency

Treatment Methods

Loading dose: 50,000 IU cholecalciferol weekly for 8-12 weeks

Maintenance dose: 1,000-2,000 IU cholecalciferol daily

Calcium supplementation in severe deficiency

Sun exposure 15-20 minutes daily

High-dose oral or IM/IV formulations in malabsorption

Which Department to Visit?

You can visit our Dahiliye (İç Hastalıkları) department for these complaints. Our specialist physicians will create the most suitable treatment plan for you.

Learn About Dahiliye (İç Hastalıkları) Department

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You can make an appointment with our specialists or contact us for your concerns.

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Health Disclaimer: The information on this page is prepared for general informational purposes only. It does not replace medical diagnosis and treatment. Please consult your physician for your complaints. Saygı Hospital does not accept responsibility for actions taken based on the information on this page.