Infancy onset hypocalcemia due to maternal vitamin D deficiency

Bogdan Pascu; Carla Ciobanu

Hypocalcemia is a common metabolic problem and a recognized cause of seizures in neonates and infancy. Breastfed infants born to mothers who are vitamin D and or calcium deficient are at risk of developing vitamin D deficiency and hypocalcemia.

Case report: We present two infants (two weeks old boy and a 9-month-old girl) with hypocalcemia caused by vitamin D deficiency admitted to our pediatric emergency department for seizures and tetany. Both were born at term with normal weight, exclusively breastfed since birth and not receiving vitamin D supplements. Both mothers were having average nutritional diet and no or irregular vitamin D supplements. Symptomatology started a few days before the admission. The seizures were not associated with fever, lethargy, or feeding abnormalities, and the clinical examination did not reveal any dysmorphic facies. Laboratory investigations: revealed low ionized calcium and total calcium corrected for serum albumin indicating true hypocalcemia, modestly low magnesium with no evidence of significant hypomagnesemia causing impaired PTH secretion, phosphorus, and alkaline phosphatase in the normal range, and an elevated PTH in response to hypocalcemia.

Table 1. Investigations related to hypocalcemia.
	Case 1	Case 2
Age	2 weeks	9 months
Serum			Normal values
Calcium(mg/dl)	7.5	4.7	8.6-10.2
Ionized calcium(mmol/l)	1.04	0.68	1.12-1.35
Magnesium(mmol/l)	0.60	0.62	0.65-1.05
Phosphorus(mmol/l)	3	1.70	1.2.9
PTH(pg/ml)	49.80	76.40	9.2-44.6

Further investigations showed a low 25(OH)D in both infants, confirming vitamin D deficiency. 24-hour urine examen showed calcium and the urinary calcium to creatinine ratio within normal limits, low urinary phosphorus and magnesium. Thyroid ultrasound detected thyroid and parathyroid glands with normal structure and dimensions. Thyroid function was also normal. Testing in both mothers found low levels of vitamin D and the cause for vitamin D deficiency was attributed to maternal vitamin D deficiency.

Table 2: Vitamin D biochemical parameters in infant-mother
	Case 1		Case 2
	Infant	Mother	Infant	Mother
25(OH)VIT D (nmol/l) (75-175nmol/l)	34.70	20.20	<20.20	31.70

Management and treatment: Calcium gluconate infusion and vitamin D were initiated with favourable evolution.

Discussion: Vitamin D deficiency is an important predisposing factor for symptomatic hypocalcemia in young infants and maternal vitamin D deficiency is a risk factor for its deficiency during infancy. There is a need to assess the vitamin D status of all pregnant and lactating women and to consider routine vitamin D supplementation for breastfed infants and pregnant women.

ESPE Abstracts

P2-306