OCCULT LEAD-INTOXICATION AS A CAUSE OF HYPERTENSION AND RENAL-FAILURE

Background. The true incidence of lead (Pb) overload as a cause of chr onic renal failure (CRF) is unknown. Also, it is unclear if CRF per se could generate an increment in the body Pb burden. Most studies of ch ronic Pb intoxication have been performed on cohorts or patients with a past history of occupational exposure. Therefore we studied the body Pb burden in CRF of known aetiology versus those patients with CRF wi th gout and hypertension of unclear aetiology without a past history o f Pb exposure. In addition we studied patients diagnosed with essentia l hypertension. Methods. We studied 296 patients lacking a past histor y of Pb exposure, who were subdivided into four groups: group I (n=30) , normal control subjects; group II (n=104), patients with 'essential' hypertension and normal renal function; group III (n=132), patients w ith CRF of uncertain aetiology in association with hypertension and/or gout, and group IV (n=30), patients with CRF of known aetiology. The blood and urine Pb levels were assessed before and after an EDTA test. Results. No abnormal test results were obtained for patients in group s I and IV. The EDTA test was abnormal in 16 patients (15.4%) in group II and in 74 patients (56.1%) in group III. A positive correlation wa s observed between plasma creatinine levels and post-EDTA urinary Pb i n group III, but not in group I. No correlation regarding plasma creat inine and the duration of hypertension or gout were demonstrated. The bone Pb levels, measured in 12 patients with pathological EDTA test re sults, were positively correlated to the plasma creatinine levels. Con clusions. A high percentage of patients with gout, hypertension, and C RF have an excessive Pb burden, and about 15% of the patients diagnose d as 'essential' hypertensives also show high Pb burdens. It is remark able that a history of overt Pb exposure was lacking in the whole stud y population.