Objective
To discover the mechanism of hypocalcemia in a patient with the CHARGE (coloboma, heart disease, atresia choanae, retarded growth and development, genital hypoplasia, and ear anomalies) association.
Research Design
Chemical and metabolic studies of serum, urine, stool, and muscle specimens.
Setting
A university hospital affiliated with a municipal hospital.
Participant
One patient with the CHARGE association and refractory hypocalcemia.
Measurements and Results
Serum calcium level was 0.91 mmol/L (reference range, 2.20 to 2.58 mmol/L and serum magnesium level was 0.34 mmol/L (reference range, 0.80 to 1.20 mmol/L) prior to any therapy. After parenteral calcium and magnesium therapy, hypocalcemia persisted (1.46 mmol/L), while the serum magnesium level was 0.84 mmol/L. A needle biopsy of skeletal muscle tissue for the magnesium content confirmed a total magnesium deficiency despite normomagnesemia (muscle magnesium content, 517 µg/g [reference range, 800 to 1100 µg/g]). Magnesium deficiency was secondary to secretion of magnesium into the gastrointestinal tract (with a daily magnesium intake of 190 mg, a 24-hour nondiarrheal fecal excretion of magnesium was 2019 mg/kg [reference range, <1000 mg/kg of stool weight]).
Interventions
Hypocalcemia was corrected only after 7 weeks of continual parenteral magnesium supplements to replenish the tissue magnesium deficiency.
Conclusions
Patients with the CHARGE association often have hypocalcemia. Magnesium deficiency (with or without hypomagnesemia) is a cause of the hypocalcemia in at least one patient and may prove of significance in others.
(Arch Pediatr Adolesc Med. 1994;148:486-489)
