Hearing status in children with frequently relapsing and steroid resistant nephrotic syndrome

Children with idiopathic nephrotic syndrome (INS) are at risk of hearing impairment due to nephrotoxic drugs and biochemical impairments.

Forty children with INS aged 5-16 years [20 patients with frequently relapsing nephrotic syndrome (FRNS)/steroid dependent nephrotic syndrome (SDNS) and 20 with steroid resistant nephrotic syndrome (SRNS)] and 20 normal healthy controls were enrolled in this study. Pure tone audiometry was done using the ALPS AD 2000 audiometer. Sensorineural hearing loss was diagnosed when the bone conduction level was >20 dB and the difference in air to bone gap was ≤15 dB. Based on the air conduction (AC) threshold, deafness was graded into the following categories: mild (26-40 dB), moderate (41-55 dB), moderately severe (56-70 dB), severe (71-91 dB) and profound (>91 dB).

Children with FRNS/SDNS had a higher threshold for hearing at frequencies of 250 and 500 Hz, respectively, than the controls. Of the children in the FRNS/SDNS category, three (15 %) had mild sensorineural hearing impairment. These children had a low serum calcium level (P < 0.03) and received higher cumulative doses of furosemide (P < 0.04). Children with SRNS had a higher threshold for hearing at frequencies of 250, 500, 1,000, and 2,000 Hz, respectively, than the controls. Of the 20 children with SRNS, ten (50 %) had sensoineural hearing impairment (8 mild, 2 moderate). Children with SRNS with a hearing defect had received a higher cumulative dose of furosemide (P < 0.03).

Children with FRNS/SDNS and SRNS are at risk of sensorineural hearing impairment. The risk factors associated with this impairment were higher cumulative doses of furosemide and hypocalcemia. Larger prospective cohort studies are required to evaluate this association.