Hypokalaemia and hyperkalaemia — OSCE

Candidate brief

You are the paediatric registrar. Your daughter is 14 and has had cramps and tingling for two years, worse recently. The team has confirmed a genetic kidney condition called Gitelman syndrome. The parents want to understand what it is, whether it is curable, why their daughter needs magnesium as well as potassium, what the treatment involves day to day, and what to watch for. Explain clearly, check their understanding, and agree a plan. [9]

Marking domains

Clinical knowledge and accuracy (3). Explains that Gitelman syndrome is an inherited defect of the kidney's distal tubule that wastes salt, potassium and magnesium; that it is lifelong but not life-shortening with treatment; and that the low magnesium is central because it both causes symptoms and prevents potassium from being retained. [9][10]

Communication and plain language (3). Avoids jargon or defines it; uses an analogy (the kidney tubule is a "filter with a leak"); paces the information; pauses to check understanding; invites questions. Conveys that it is genetic but usually inherited from both parents (autosomal recessive) and does not imply anything was done wrong. [9]

Management plan and safety-net (3). Explains the lifelong potassium and magnesium supplements, the role of a potassium-sparing diuretic, the need for regular blood tests and monitoring of growth and kidney function, and the transition to adult kidney care. Gives a clear safety-net: seek help for severe weakness, palpitations, collapse, or inability to keep tablets down; flag the condition and the medications to any new doctor. [4][10]

Empathy and partnership (1). Acknowledges the two-year search for an answer, validates the family's concern, and frames the diagnosis as a positive step — a named, treatable condition with a clear plan. [4]

Examiner notes

Strong candidates explain WHY magnesium matters (it is both symptomatic and the reason potassium was refractory), name the inheritance pattern correctly, and give a concrete safety-net rather than vague reassurance. Weak candidates call it "a kidney problem," omit the magnesium, or offer a cure. [4][9]