Lupus nephritis patients may have Idiopathic hypokalemia, finds study

Number of outpatient population undergoing laboratory testing, mild hypokalemia can be found in almost 14%. Kidney functioning is greatly affected by Hypokalemia.

Hypokalemia may occur in patients with Lupus Nephritis in the absence of Renal Tubular Acidosis (RTA) or other known causes finds a new study by Dr Emmanuel A. Adomako and team. Further patients with lupus nephritis and idiopathic hypokalemia have a distinct pattern of markers of autoimmunity. The study is published in Kidney 360 journal.

The objective of the study was to report the incidence of hypokalemia in Lupus Nephritis (LN) patients.

The study was a population study of 403 patients with LN, we identified a cohort of 20 patients with idiopathic hypokalemia (HK), defined by serum potassium < 3.5 mmol/L without any apparent explanation. This cohort is compared to 90 LN controls (CON) and 10 LN patients with distal renal tubular acidosis (RTA) from the same population.

The results of the study were found to be

• The HK cases had lower median serum potassium compared to CON and RTA subjects (3.26 vs 4.00 vs 3.75 mmol/L, respectively; p < 0.001). The median serum bicarbonate was normal in HK and CON but low in RTA (26.0 vs 25.0 vs 19.4 mmol/L; p < 0.001).

• The median urine pH was abnormally high only in the RTA group (6.00 vs 6.25 vs 6.67; p = 0.012). The median serum magnesium was modestly lower in HK compared to the CON and RTA groups (1.73 vs 2.00 vs 1.85 mg/dL; p = 0.002).

• While both HK and RTA showed a higher rate of seropositivity than CON for anti-Ro/SSA (79% and 80% vs 37%, respectively; p < 0.001), only HK revealed a higher rate of seropositivity than CON for anti-RNP (84% vs 42%; p = 0.003) and only RTA showed a higher rate of seropositivity than CON for anti-La/SSB (40% vs 12%; p = 0.046).

Dr Adomako and team concluded that "A syndrome of idiopathic hypokalemia was revealed in 20/403 (5%) of patients within our LN population and proved to be distinct from the renal tubular acidosis that occurs in LN. Furthermore, it was associated with a distinct pattern of autoantibodies. We speculate that idiopathic hypokalemia is the result of a novel target of autoimmunity in LN affecting renal tubular potassium transport."

For further information: https://doi.org/10.34067/KID.0004352021