#2830 Treatment of primary and secondary distal renal tubular acidosis with a prolonged release formulation of potassium citrate and potassium bicarbonate

Abstract

Abstract Background and Aims Distal renal tubular acidosis (dRTA) is a rare kidney disease. It can be inherited, i.e. primary (PdRTA), or acquired i.e. secondary (SdRTA). Secondary dRTA is more prevalent in the adult population and is usually caused by underlying autoimmune diseases (e.g. Sjogren syndrome). Both forms of dRTA are characterized by alkaline urine, kidney stone formation, nephrocalcinosis, chronic kidney disease, while metabolic acidosis can be variable. The treatment is based on the substitution of alkali substances. Our clinical study aims to describe a cohort of adult dRTA patients (both PdRTA and SdRTA) treated for 18 months by a prolonged-release alkalizing formulation of potassium citrate and potassium bicarbonate, in terms of electrolyte disbalance correction, metabolic control, nephrolithiasis complications and kidney function. Method Data from seven patients with dRTA (3 with PdRTA and 4 with SdRTA, mean age 44 years, women 71%) taking prolonged-release alkalizing formulation of potassium citrate and potassium bicarbonate in our center, were retrospectively collected and analyzed. The patients were previously treated with alkalizing agents (mostly sodium bicarbonate and potassium citrate). Patients were followed up for up to 18 months after inducing prolonged-release alkalizing formulation of potassium citrate and potassium bicarbonate was introduced. Kidney function, metabolic acidosis control (serum bicarbonate), serum electrolytes, urinary calcium excretion, and urinary citrate were measured. Nephrolithiasis complications and patient compliance were also evaluated. The urine and blood samples were analyzed two weeks after introducing the new drug and every 3 months afterward. Data are presented as mean ± standard error of the mean. Student T-test was used to calculate p values. Results The patients were taking on average 48 mEq of the drug (range 32-72 mEq), the dosage remained the same during the follow-up period (p = 0.365). The average follow-up period was 10 months (range 3-18 months). The metabolic acidosis was well controlled (serum bicarbonate was 24 ± 1.71 mmol/l at baseline, 24.4 ± 1.5 mmol/l at the end of follow-up, p = 0.680). Kidney function remained stable (GFR 73.5 ± 22.67 ml/min/1.73 m2 at baseline, 73 ± 22.69 ml/min/1.73 m2 at the end, p = 0.977). Serum potassium was also well controlled (4.07 ± 0.45 mmol/l at baseline, 4.32 ± 0.40 mmol/l at the end, p = 0.344), as well as calcium in 24-hour urine (2.75 ± 0.59 mmol/24-hour urine at baseline, 2.35 ± 0.12 mmol/24-hour urine at the end, p = 0.222). Urinary citrate levels (calculated as citrate/creatinine ratio) remained in the lower part of the reference range during the follow-up period (103.3 ± 68.3 mmol/mol at baseline, 114.6 ± 64.9 mmol/l at the end, p = 0.775). Two patients had acute renal colic caused by nephrolithiasis, without the need for surgical intervention. Safety and adherence to treatment remained good with no gastrointestinal side effects, one patient discontinued the drug due to headaches. Conclusion Our data show that treatment with a prolonged-release alkalizing formulation of potassium citrate and potassium bicarbonate in adult dRTA patients can achieve good control of metabolic acidosis and electrolyte disbalance with stable kidney function without the need to escalate the dose of the drug during the follow-up period. The adherence to the treatment remained good with no gastrointestinal side effects.