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• Credits

  • Section Writer: Dr. Om J Lakhani
  • Section Editor: Dr. Om J Lakhani

• Linked notes

  • Physiology and Metabolism of Vitamin D

• Laboratory Assessment of Vitamin D

• Q. Which is the principal storage form of vitamin D, and what is its half-life?

  • Storage form is 25-Hydroxyvitamin D
  • Half-life is 15 days

• Q. Give the definitions of vitamin D deficiency and insufficiency?

  • Vitamin D levels
    • Deficiency <20 ng/ml
    • Insufficiency – 20-29 ng/ml
    • Sufficiency – 30-100 ng/ml
    • Toxicity – >150 ng/ml

• Q. Give the cutoffs for vitamin D in nmol/l

  • <30 nmol/l – inadequate
  • 30-50- insufficiency
  • 50-75- sufficiency
  • 75-125- no benefit of replacement
  • More than 125- toxicity

• Q. Where do these levels for normality come from?

  • They are based on when the PTH level rises

  • Hence they are correlated with PTH level

  • Q. Which is better for Vitamin D assessment- immunoassay or mass-spectrometry?

    • Mass spectrometry is more reliable
    • This is because immunoassay has a lot of variation

  • Q. Which correlates better with signs and symptoms of vitamin D deficiency- 25-Hydroxyvitamin D level or 1,25 Dihydroxyvitamin D?

    • 25 hydroxyvitamin D levels correlate better with clinical features of vitamin D deficiency

  • Q. When should 1,25 Dihydroxyvitamin D levels be measured?

    • Cases of hypercalcemia
      • Calcitriol intoxication
      • Hypercalcemia due to granulomatous disorder
      • PTH dependent hypercalcemia
    • Cases of hypocalcemia
      • CKD
      • Tumor induced osteomalacia
      • Hereditary disorders of vitamin D deficiency

• Treatment of Vitamin D deficiency

  • Q. Give the Recommended daily allowance (RDA) of Vitamin D?

    • infants- 400 IU
    • Children- 600 IU
    • Adults (<70 years)- 600 IU
    • Elderly (>70)- 800 IU
    • Pregnant and Lactating- 600 IU
    • 
    • 

  • Q. How do you treat vitamin D deficiency in Adults?

    • Cholecalciferol 60,000 IU once a week for eight weeks
    • Followed by Cholecalciferol 2000 IU once a day (60,000 IU once a month)
    • Maintain Vitamin D at a level of 30-50 ng/ml for maximum health benefit

  • Q. What is the dose required for vitamin D maintenance?

    • 1.  Infants- 400 IU/day
    • 2. Children – 1000 IU/day
    • 3.  Adolescents- 1000-2000 IU/day
    • 4.  Adults- 2000 IU/day

• Vitamin D Deficiency - Indian guidelines

  • Q. How common is vitamin D deficiency in India?

    • 70-98%

  • Q. What vitamin D levels are associated with Rickets and Osteomalacia?

    • Vitamin D level of <5 ng/ml

  • Q. What level is associated with Secondary hyperparathyroidism?

    • ^^<15 ng/ml are associated with Secondary hyperparathyroidism^^

  • Q. Is vitamin D deficiency also present in Rural India?

    • Yes

  • Q. For which patients are 20 ng/ml optimal and for which is 30 ng/ml optimal?

    • Vitamin D >20 ng/ml is optimal for most adults
    • Levels of >30 ng/ml- must be achieved in older adults > 50 years of age and patients with osteoporosis

  • Q. What should be the daily intake of vitamin D in adults?

  • Guidelines recommend 1000-2000 IU / day

    • In Indians, since most are deficient – 2000 IU/day is recommended
    • Levels up to 4000-5000 IU/day are safe
    • Levels >10,000 IU/day are associated with toxicity

  • Q. Vitamin D testing must be done in which patients?

    • Those with clinical features of vitamin D deficiency like osteomalacia and rickets
    • Those with a high risk of having vitamin D deficiency
      • Anti-epileptics
      • Anti-retrovirals
      • Antitubercular
      • glucocorticoids
      • Ketoconazole
      • bariatric surgery
      • IBD
      • CKD
      • CLD

  • Q. When is 1,25 dihydroxy vitamin D measured?

    • Granulomatous disease
    • Tumor induced osteomalacia
    • Hypophosphatemic rickets
    • CKD
    • Vitamin D resistant rickets

  • Q. Which life-threatening complications can be seen in children with vitamin D deficiency?

    • Neonatal hypocalcemic seizures
    • Hypocalcemic cardiomyopathy

  • Q. What are the cutoffs for defining Vitamin D Deficiency in children?

    • <10 ng/ml- severe deficiency
    • 10-20 ng/ml- Deficiency
    • 20-100 ng/ml- Sufficiency
    • More than 100 ng/ml- Hypervitaminosis

  • Q. What is the dose of vitamin D recommended in infants?

    • Vitamin D of 400 IU is recommended in infants starting from the first few days of life

  • Q. What is the recommended dose in children?

    • Children – 1000 IU/day
    • Adolescents- 1000 -2000 IU/day- higher dose in obese adolescents of 2000 IU/day

  • Q. What is the dose recommended in children for the treatment of rickets?

    • <1 year
      • 1000-2000 IU/day for eight weeks
    • 1-12 years
      • 2000-4000 IU/day for 8 weeks
      • 60,000 IU every 2 weeks for 8 weeks
      • 150,000 IU IM – rpt dose after 6 weeks if required
    • More than 12 years
      • 2000  -4000 IU/day
      • 60,000 IU/week x 8 week
      • 3 lac IU IM – rpt after 6 weeks if needed

  • Vitamin D and Pregnancy

    • #ClinicalPearl: Vitamin D deficient mothers have vitamin D, deficient infants

    • Q. What are the impact of vitamin D deficiency on the mother?

      • Pre-eclampsia
      • GDM
      • Bacterial infection of the vagina

    • Q. What is the impact of maternal vitamin D deficiency on the fetus?

      • Neonatal hypocalcemic seizures
      • Hypocalcemic cardiomyopathy
      • Low birth weight
      • Rickets

    • Q. What level is considered a deficiency in pregnancy?

      • <20 ng/ml

    • Q. Should all pregnant women be tested for vitamin D deficiency?

      • No. It is not necessary
      • It can be done if economically feasible

    • Q.  What is the dose of vitamin D in pregnancy?

      • Advised only after 1st trimester – ie, 12 weeks
      • Ideally, correct vitamin D deficiency before conception
      • After conception
        • 1000 IU- in all women
        • 2000 IU- in women with a high risk of deficiency
        • 4000-5000 IU /day – Shown to be safe can be used if deficiency established
        • Weekly and monthly dose – not recommended as the first choice but can still be used

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