Critically interpret and evaluate the data given in this case

Question:

Peter visited his GP as he was feeling ‘unwell’. The GP was concerned that his kidney function might be impaired and collected a blood sample to measure his serum creatinine concentration (see table below). Peter is 44 years old and his left leg was amputated above the knee when he was a child.

Analyte Patient sample Reference Range Units
Serum creatinine 90 50-120 μmol/L
eGFR (CKD-EPI creatinine) 89 >60 ml/min/1.73m2

Critically interpret and evaluate the data given in this case. Your answer should include an explanation of what serum creatinine and eGFR are and how they are used in assessing renal function.