A spurious decline in kidney function: A reality check.

Abstract

A man aged 70 years was referred to a renal clinic by his general practitioner for evaluation of a decline in his renal function. He had a history of hypertension, for which he was taking perindopril and amlodipine in combination, and left nephrectomy for renal cell carcinoma in 2013. A drop in his estimated glomerular filtration rate (eGFR) from a baseline of approximately 70 mL/min in February 2019 to 51 mL/min in May 2019 was noted with no obvious cause. His perindopril was withheld in view of this decline. However, by the time he was reviewed in the clinic, his renal function had recovered and he had recommenced perindopril. On perusing his blood tests, it was noted that he had significantly different eGFR reported for the same serum creatinine value (eGFR of 51 mL/min and 68 mL/min for a serum creatinine value of 98 mumol/L). Between May and August 2019, when a lower eGFR was reported, the serum creatinine reference range for females (45-85 mumol/L) had been used instead of that for males (60 -115 mumol/L). The patient's results are shown in Table 1. The patient had a unisex first name, likely resulting in an inadvertent biological sex misassignment and a spuriously low eGFR. This was subsequently corrected, resulting in an improvement in his eGFR. On contacting the reporting laboratory, it was established that the correct biological sex had been ascribed to the patient on the request form, but the error had occurred at the level of the laboratory, likely from an error of manual transcription.