Late onset hypocalcemia occurs beyond the initial neonatal period. This is usually not seen in breast fed infants.


Time period: 5 days to 6 weeks after delivery


Causes of hypocalcemia:

(1) diet high in phosphate (cow's milk or infant formula). This can result in an elevated serum phosphate concentration. It can also precipitate calcium in the diet as calcium phosphate.

(2) decreased responsiveness of immature parathyroid glands to the elevated phosphate

(3) concomitant vitamin D deficiency

(4) concomitant hypomagnesemia


Clinical manifestations:

(1) convulsions

(2) laryngospasm

(3) irritability and muscle tremors

(4) ECG abnormalities (prolonged QT interval, conduction abnormalities)

(5) rarely heart failure


Laboratory findings:

(1) low serum calcium concentration

(2) high serum phosphate concentration

(3) normal serum creatinine (to exclude severe renal dysfunction as the cause of the elevated phosphate)


Differential diagnosis:

(1) severe renal dysfunction

(2) meningitis

(3) intracerebral hemorrhage

(4) hypoparathyroidism


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