Endocrine Abstracts

Introduction: Type IV Renal Tubular Acidosis (Type 4 RTA) is an underdiagnosed condition known to be more frequent in Diabetes Mellitus patients with moderate renal impairment. It is thought to be very common, with an incidence of 3.8% of hospital admissions in some series, being an increasing problem among the elderly and aggravated by polypharmacy.

Methods/design: The authors describe 4 cases of Type 4 RTA associated with type 2 Diabetes diagnosed and followed in the Endocrinology department of Hospital de Egas Moniz.

Results: The population studied had an average age of 67 years, mean Diabetes duration of 8 years and all had arterial hypertension and hypercholesterolemia. All patients were on insulin therapy and had some degree of chronic renal disease. None suffered from coronary artery disease and only one had cerebrovascular disease. 75% had the full microvascular burden (nephropathy, retinopathy and neuropathy). Mean time from hyperkalemia onset and type 4 RTA diagnosis was 17.2 months. Mean glycated hemoglobin during follow up was 8.7%. Mean glomerular filtration (CKD-EPI) rate at type 4 RTA diagnosis was 40.3 ml/min/1.73m². The average number of hospital admissions was 5. Only one patient required therapy with fludrocortisone.

Conclusion: Type 4 RTA is often a late diagnosis in type 2 Diabetes. In our small series we documented a high microvascular complication burden. The associated hyperkalemia poses a significant threat to the affected patients, which often have a limited cardiovascular reserve. Timely diagnosis and adequate treatment are essential for optimizing patient care.