Unklare chronische Hypokaliämie bei einer jungen Frau

HISTORY AND CLINICAL FINDINGS: The 27year old female patient presented with chronic hypokalaemia knownfor 6 years and current potassium values of 1.8 mmol/l.She reported having diarrhea for a few days, fever was denied. INVESTIGATIONS: Physical examinationrevealed dry skin and mucosa and a slim nutritional status, laboratoryinvestigations showed a hypokalaemic, hypochloraemic alkalosis andhypomagnesaemia. Our first suspicion was an eating disorder or abuseof diuretics or laxatives. Urine analysis showed a high concentrationof potassium and chloride, a screening for diuretics was negative.Due to the electrolyte constellation we assumed a Gitelman’sSyndrome which was confirmed by genetic testing. TREATMENT AND COURSE: After intravenoussubstitution of potassium and cessation of diarrhea the potassiumvalues stabilised at 2.5 - 3.0 mmol/l.After being discharged she continued oral substitution of potassiumand no such period of severe hypokalaemia occurred again. CONCLUSION: Establishing a diagnosisfor patients with chronic hypokalaemia may present difficulties.Urine analysis can help to find reasons for electrolyte disorders.Via measurement of urinary chloride concentration repetitious vomitingas stigmatising diagnosis could be excluded. Urine analysis alsoled to the diagnosis Gitelman syndrome, an inherited renal tubulardisorder, which is suspected to count for 50 % ofunexplained chronic hypokalemia.