Bartter syndrome (BS) is a congenital salt-wasting tubulopathy with an induced expression of cyclooxygenase-2 in the macula densa leading to hyperreninemia. Renin Angiotensin Aldosterone system (RAAs) activation leads to hypokalaemic alkalosis. NSAIDs are now currently used in BS, however few studies have investigated the effect of NAIDs on RAAs activation, biological parameters and treatment modifications.

We included 19 patients with BS treated with NAIDs between 1994 and 2016. We assessed renin and aldosterone serum levels, serum electrolytes, calcium, phosphorus, Vitamin D and PTH before and after treatment initiation. We also recorded modifications in sodium and potassium supplements and adverse events.

Median age and weight at treatment initiation were 7 [4–49] months and 6175 [4360–13,675]grams respectively. Serum renin and aldosterone levels significantly decreased from 1532 [952–2638] to 226 [132–704]pg/mL (P<0.001) and from 380 [206–1100] to 229 [64–301]ng/mL (P=0.02) respectively. There was a trend towards an increased kalaemia [2.9 (2.4–3.5) to 3.3 (2.9–3.9), P=0.17]. NSAIDs allowed a major reduction of oral sodium supplements from 10.8 [5.4–14] to 6.3 [2–10.1]mEq/kg/day and from 3.8 [1.7–9.0] to 1.7 [0.5–5.2]mEq/kg/day of potassium (P<0.001). We also found a significant decrease of the calciuria from 3.9 [1.5–4.8] to 1.2 [0.2–2.4] mmol/mmol of creatininuria (P=0.02). Nine patients presented a high serum PTH level among whom eight completely normalized after treatment without any modification of the vitamin D and calcium supplements. Four patients presented gastro-intestinal complications.

In this report, we confirm the major benefit of NSAIDs treatment in patients with BS. We also assess that monitoring renin serum level is of interest to adapt patients’ treatments. Finally, we demonstrate a beneficial effect of NSAIDs both on the decrease of the calciuria and the decrease of bone turn-over.