Solving a weightlifter’s renal riddle in a case of misdiagnosed CKD

An inexplicable abnormal result highlights the role of a little known test, cystatin C, when assessing kidney function in those at the extremes of muscle mass

Simon, aged 56, takes pride in his good health. He works long hours as a bank manager, but also prioritises maintaining a healthy lifestyle and regular exercise.

He is well, a non-smoker, and takes no medications. He eats whole foods, mostly low carb with plenty of protein. He lifts weights at the local gym three times a week.

When Simon books in with his GP for a routine checkup, he says he feels great. The GP notes that he has coeliac disease, and that there is no family history of diabetes, or cardiovascular or renal disease.

On examination, Simon appears to be a healthy middle-aged male. His weight is 74kg, height 178cm, waist circumference 85cm and BMI 23.4kg/m2.