RESUMO
INTRODUCTION: Despite increasing use in clinical practice, an estimated glomerular filtration rate value (eGFR) of <60 ml/min/1.73 m2 does not necessarily indicate the existence of chronic renal insufficiency (CRI) and this may lead to an over-estimate of CRI particularly in persons seventy years or older. AIM: To find a screening test able to differentiate CRI from the decrease in GFR normally associated with the renal ageing process. METHODS: Medical information of 487 individuals of both sexes aged 16-102 was obtained from nephrologists, internal medicine physicians, cardiologists, geriatricians, family and nuclear medicine doctors from Argentina, Portugal and Spain. Data were assessed and statistically analysed using logistic regression techniques. From the discriminative variables it was derived the HUGE formula. RESULTS: A formula including haematocrit , blood urea, and gender (HUGE), diagnoses CRI regardless of the variables of age, blood creatinine, creatinine clearance, or other eGFR. The HUGE formula is: L = 2.505458 - (0.264418 x Hematocrit) + (0.118100 x Urea) [+ 1.383960 if male]. If L is a negative number the individual does not have CRI; if L is a positive number, CRI is present. Our data demonstrate that the HUGE formula is more reliable than MDRD and CKD-EPI, particularly in persons aged over 70. CONCLUSIONS: Our HUGE screening formula offers a straightforward, easily available and inexpensive method for differentiating between CRI and eGFR < 60 ml/min/1.73 m2 that will prevent a considerable number of aged healthy persons, as much as 1.700.000 in Spain and 2.600.000 in U.K., to be excluded from clinical assays or treatments contraindicated in CRI.