1213 A Boy with Hyperkalemia and Hypertension without Family History: Still Pseudohypoaldesteronism (Gordon Syndrome)?

Abstract

Background and Aims We report a 6-year-old boy presenting with macroscopic hematuria, hyperkalemia and hyperfosfatemia. Results A 6-year-old boy presented to our outpatient clinic with hematuria. No clinical abnormalities were found, besides borderline hypertension of 120/60mmHg (P95 adjusted for height and age 100/57). Laboratory testing revealed a serum potassium of 8.6 mmol/l and a phosphate of 6.2mg/dl. During admission hyperkalemia appeared refractory to standard treatment with furosemide, salbutamol and alkalinisation. Prompt reduction of hyperkalemia was observed after a trial with hydrochlorothiazide, suggesting the diagnosis of pseudohypoaldesteronism. Further testing revealed a high aldosteron of 537 pg/ml. Familial history was negative but still a suspicion of pseudohypoaldosteronim remained, so genetic testing was performed. A de novo splice site mutation was found in the CUL3-gene (c.1377+1G>A) leading to a skipping of exon 9. Conclusions We present an atypical presentation of Gordon syndrome (familial hyperkalemic hypertension) due to a de novo splice mutation. The clinician should be aware of this possibility when facing a child with high serum potassium.