Woman with Hypomagnesemia and Hypocalcemia

Summary

DOI: 10.1373/clinchem.2014.229005

A 71-year-old woman was referred to the endocrinology clinic after several years of unresolved hypomagnesemia that required numerous hospital admissions to receive intravenous magnesium. She previously presented with palpitations on 3 occasions, and once with diarrhea and vomiting.

Student Discussion

Student Discussion Document (pdf)

Adie Viljoen,^1* Becky Batchelor,² and Azad Ghuran²

Departments of ¹Clinical Biochemistry and; ²Cardiology, Lister Hospital, Stevenage, UK.
*Address correspondence to this author at: Department of Clinical Biochemistry, Lister Hospital, Corey’s Mill Lane, Stevenage SG1 4AB, UK. E-mail [email protected].

Case Description

Her medical history included type 2 diabetes mellitus and hiatal hernia. Her regular medications included simvastatin, esomeprazole, verapamil, pioglitazone, gliclazide, metformin, and calcium, magnesium, and vitamin D supplementation. Clinical examination in the endocrinology clinic was unremarkable, and no abnormality was demonstrated on electrocardiogram. An echocardiogram was normal.

Laboratory results at this visit included serum magnesium 0.52 mg/dL (0.21 mmol/L) [reference interval 1.7–2.4 mg/dL (0.7–1.0 mmol/L)] and serum calcium 6.84 mg/dL (1.71 mmol/L) [reference interval 8.8 –10.6 mg/dL (2.20 –2.65 mmol/L)]. Serum albumin was 35 g/L (reference interval 35–52 g/L). The results of her other biochemical tests were unremarkable. Twenty-four- hour urine magnesium excretion was undetectable [reference interval 0.5–1.2 mg/dL (0.2–5.0 mmol/24 h)], as was random urine magnesium [0.25 mg/dL (0.1 mmol/L)]. Intact parathyroid hormone (PTH) was 20 ng/L (reference interval 15– 88 ng/L), inappropriately low in the presence of hypocalcemia. All analytes were measured with a Beckman Olympus AU2700 general chemistry analyzer with the exception of intact PTH, which was measured with a Beckman Coulter Access II.

The patient gave full written consent for the use of her clinical information and laboratory tests for the purposes of a case report in the medical literature.

Table 1. Laboratory results during previous visits

Questions to Consider

What are the common causes of hypomagnesemia?
Are any of the patient’s medications potential causes of hypomagnesemia?

What effect does magnesium have on calcium and parathyroid hormone?

Final Publication and Comments

The final published version with discussion and comments from the experts appears in the May 2015 issue of Clinical Chemistry, approximately 3-4 weeks after the Student Discussion is posted.

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