A 50-year-old patient was admitted to the ICU for airway observation following a difficult parathyroidectomy. No immediate airway problems were evident. About 24 hours later, the patient was noted to be in fast atrial fibrillation, and complained of difficulty in breathing with generalised aches and pains.

a) What is the likely explanation for the patient's symptoms?

b) List your specific management for this problem.

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College Answer

a) Hypocalcaemia and possibly hypomagnesaemia causing muscle cramps, possible laryngospasm.

b)
 Ca gluconate or chloride – bolus or infusion.
 Mg supplements.
 Anti-arrhythmics for AF.

Discussion

That this is hypocalcemia, and that replacing calcium is the solution, does not require extensive discussion.

Post-parathyroidectomy hypocalcemia is the most likely guess for this disturbance, given that it's the complication everybody watches for whenever a patient's parathyroid glands have been surgically interfered with. It happens to some extent in over half of the patients undergoing this surgery (Mittendorf et al, 2004). Of the symptoms, the most common are "acral or perioral numbness and paresthesias, muscle cramps, or, in more severe cases, laryngeal stridor, tetany, generalized seizures, and cardiac arrhythmias". The difficulty breathing could also be pulmonary oedema. Lekas et al (2010) discussed how this might happen, pointing out the essential role of calcium in contractility and diastolic relaxation. 

Hypomagnesemia after parathyroid surgery is also a thing, albeit not as well-known. Jones et al (way back in 1973) described it in a way which makes it look much like severe hypocalcemia, which it is often associated with. By treating the mganesium, the symptoms disappear even if the calcium level is ignored. "Despite persistence of severe hypocalcaemia the acute restoration of the serum magnesium level to normal with intravenous therapy was accompanied by a striking alleviation of the clinical abnormalities" the authors remark. One cannot help but think that one should still think about replacing the missing calcium anyway (for one, the blood still needs to clot somehow).

References

References

Mittendorf, Elizabeth A., James I. Merlino, and Christopher R. McHenry. "Post-Parathyroidectomy Hypocalcemia: Incidence, Risk Factors, and Management/DISCUSSION." The American surgeon 70.2 (2004): 114.

Lekas, Poli, Patricia T. Goldenstein, and Joanne M. Bargman. "Myocardial dysfunction and pulmonary edema post parathyroidectomy: the role of hypocalcemia." Adv Perit Dial26.4 (2010): 125-129.

Jones, C. T., R. A. Sellwood, and J. M. Evanson. "Symptomatic hypomagnesaemia after parathyroidectomy." British Medical Journal 3.5876 (1973): 391.