Autosomal dominant hypoparathyroidism with severe hypomagnesemia and hypocalcemia, successfully treated with recombinant PTH and continuous subcutaneous magnesium infusion.
Activating calcium sensor receptor (CaSR) mutations often present with hypocalcemia and hypomagnesemia. Severe hypocalcemia with this mutation has been reported but severe hypomagnesemia has not been well described.


OBJECTIVE
To identify the cause of severe hypocalcemia and hypomagnesemia in a young child, and explore the efficacy of continuous subcutaneous magnesium therapy as a safer alternative to intravenous magnesium.


METHODS
A 2-8/12 year-old female with severe hypocalcemia and hypomagnesemia of unknown etiology.


METHODS
Genetic analysis was performed on the proband and both parents. The proband was treated with human parathyroid hormone (teriparatide) and a continuous infusion of subcutaneous magnesium sulfate initially using a Deltec insulin pump and subsequently a Curlin infusion pump.


RESULTS
The patient has a known de novo mutation in the CASR gene (A843E). She could not be adequately managed with enteral and intravenous electrolyte replacement even after adding teriparatide. She responded well to adjunctive therapy with continuous subcutaneous magnesium.


CONCLUSIONS
Severe hypomagnesemia can be part of the phenotype of activating CaSR mutations. Subcutaneous magnesium should be considered in patients with difficult to control hypomagnesemia.
Division of Endocrinology, Department of Pediatrics, UC San Diego School of Medicine, La Jolla, CA, USA. ssanda@benaroyaresearch.org
Srinath
S
Sanda
Karl P
KP
Schlingmann
Ron S
RS
Newfield
D002118:Calcium / Q000378:metabolism; D002675:Child, Preschool; D004252:DNA Mutational Analysis; D005260:Female; D005799:Genes, Dominant; D006801:Humans; D006996:Hypocalcemia / Q000188:drug therapy* / Q000209:etiology; D007011:Hypoparathyroidism / Q000150:complications / Q000188:drug therapy* / Q000235:genetics; D008275:Magnesium Deficiency / Q000188:drug therapy* / Q000209:etiology; D008278:Magnesium Sulfate / Q000008:administration & dosage / Q000378:metabolism / Q000627:therapeutic use*; D010281:Parathyroid Hormone / Q000008:administration & dosage / Q000235:genetics / Q000627:therapeutic use*; D011994:Recombinant Proteins / Q000008:administration & dosage / Q000627:therapeutic use*
C470125:PTH protein, human; D010281:Parathyroid Hormone; D011994:Recombinant Proteins; D008278:Magnesium Sulfate; D002118:Calcium