Magnesiopenic hypoparathyroidism in an infant of diabetic mother

Background:

Magnesium deficiency impairs the secretion of parathyroid hormone and may result in hypocalcemia. Little is known on the relationship between magnesium, calcium and parathyroid hormone in infancy. These factors were therefore studied in an infant of diabetic mother with magnesium depletion. Diabetes mellitus is indeed a recognized cause of magnesium depletion.

Case report:

A 2.97kg male infant was born at 38 weeks gestation by vaginal delivery to a 31-year-old woman with a well-controlled diabetes mellitus (glycosylated hemoglobin A1c 8.4%; upper reference 8.0%) on medical treatment with insulin and iron salts. Initial adaptation was well (Apgar score 8/9/10) and blood sugar levels adequate (between 2.4 and 4.3 mmol/l).

Severe normoglycemic generalized convulsions were noted starting 8 hours after birth that were treated with Phenobarbital 30mg intravenously on two occasions. Hypocalcemia (total plasma calcium between 1.32 and 1.47 mmol/l; reference value: 1.75 or more) was noted, but intravenous replacement with calcium 3.3 mmol daily failed to correct this dyselectrolytemia and the tendency towards convulsions. Hypomagnesemia (total plasma magnesium 0.31 mmol/l; reference values: 0.71–0.94), low plasma ionized calcium (0.82 mmol/l; reference values: 1.15–1.30), inappropriately low intact parathyroid hormone (12 ng/l; reference values: 9–67, two site radioimmunometric assay recognizing the entire human 1–84 molecule), and very low urinary magnesium values (urinary magnesium/creatinine 0.06mg/mmol; reference values: 0.15–0.74) were documented. Hypocalcemia and hypoparathyroidism remitted following intravenous administration of magnesium (1.2 mmol). The subsequent course was uneventful. In retrospect mild hypomagnesemia (0.65 mmol/l; reference value: 0.73 or more) was noted in the mother of the child.

Conclusion:

The present observation indicates that magnesium deficiency impairs the secretion of parathyroid hormone and may result in hypocalcemia both in adulthood as well as in infancy.