Excessive intake of vitamin D can result in toxicity (hypervitaminosis D).


Risk factors:

(1) excessive intake of nutritional supplements containing vitamin D

(2) excessive intake of milk supplemented with vitamin D

(3) administration of 1,25-dihydroxycholecalciferol


Clinical effects:

(1) in infants, failure to thrive, mental retardation, elfin facies, aortic stenosis and stenosis of the pulmonary artery

(2) hypercalcemia

(3) increased epiphyseal bone density on bone radiographs

(4) renal tubular acidosis


Features of hypercalcemia:

(1) anorexia

(2) nausea and vomiting

(3) constipation

(4) weakness and hypotonia

(5) stupor and confusion

(6) hypertension

(7) renal nephrolithiasis

(8) polyuria

(9) polydipsia

(10) cardiac arrhythmias


Laboratory findings:

(1) hypercalcemia and hypercalcuria

(2) elevation in serum 25-hydroxycholeciferol or serum 1,25-dihydroxycholecalciferol (depending on vitamin exposure)

(3) decreased levels of parathyroid hormone


Differential diagnosis for hypercalcemia and elevated serum 1,25-dihydroxy vitamin D:

(1) malignant T cell lymphoma

(2) chronic granulomatous disease


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