Is the “glomerular filtration rate” at the lowest level a sign of kidney problems?

I did some tests to measure the creatininemia and estimate the glomerular filtration rate: the first was within the low limits of the expected range; the glomerular filtration rate, for which I had never been tested, 90 (compared to the 90-120 range). At my age (62) to be considered optimal or just sufficient?

He answers Arrigo SchieppatiClinical Research Center for Rare Diseases, Mario Negri Institute for Pharmacological Research IRCCS (GO TO THE FORUM)

Your question is very interesting but also difficult to answer, because it is the question of the interpretation of estimated glomerular filtration rate (eGFR) a rather complex subject to be explained in a few words. I’ll try, hoping not to confuse you. The eGFR is a method introduced a few years ago in clinical trials to periodically monitor the kidney function of patients involved in the research. Subsequently it also spread in clinical practice, as it is believed to be able to give a fairly accurate estimate of kidney functionmore accurately than measuring serum creatinine alone and also more accurately than the creatinine clearance (which requires 24-hour urine collection, an inconvenient practice and at the risk of inaccuracies: one can forget to urinate in the bin once during the day and the collected volume data – which enters a formula – is therefore not correct).

The eGFR is calculated with a formula in which, in addition to the value of serum creatinine, gender and age contribute. While, as I said, it was once used only in the field of clinical research, now the eGFR value is automatically reported in the lab reports when the creatinine dosage is performed. This is fine, a useful fact to know. What is most criticizable is the custom of automatically associating a categorization in terms of eGFR with the estimation five classes of increasing severity of kidney damage
. In reality, the value of the eGFR itself does not allow to establish whether or not one is present nephropathy; among other things, its value can physiologically decline with age without there being a kidney disease in progress. For example, for a given creatinine value (let’s say 0.9 mg/dL, which all laboratories give in the normal range), a healthy man at age 40 has an eGFR of 106, at age 60 it is 92, and at age 80 of 80. In all three cases, the age-adjusted eGFR value. To determine whether a person has insufficient kidney disease to estimate eGFR, the overall clinical context must be assessedif there are family and personal risk factors and perform, in addition to the evaluation of renal function, a urine test to identify any abnormalities.