Are Kidney Affected by Childhood Lead Poisoning?
Many studies show there is a strong association between lead exposure and renal effects.1 Although the lowest threshold at which lead has an adverse effect on kidneys remains unknown, new studies are showing even low-level lead exposure can cause kidney damage.2 Currently, there are no early and sensitive indicators (e.g., biomarkers) considered predictive or indicative of renal damage from lead.1
Why Are Kidneys Affected by Lead?
Kidneys are affected by lead exposure because they are the main route by which lead is eliminated from the body. In this process, lead is absorbed by cells (proximal tubular cells) inside the kidneys’ duct system3 where the lead binds to specific proteins. The result are structural and functional alterations which appear to irreversible.1
What Are the Physiological Effects?
Kidney disease is chronic and non-communicable with serious consequences if not controlled effectively. Generally the progression of kidney disease develops from renal insufficiency (mild condition), to renal failure (severe condition) and then uremia (blood poisoning).
The true extent of lead exposure on kidney function is not well-characterized, but the toxic effects of lead on both children and adults are recognized as significant. Noted effects of lead exposure can involve lesions on the kidneys and decrease blood flow to parts of the kidneys which can generate tissue damage with the organ.
Acute high dose lead exposure can induced impairment of proximal tubular function resulting in aminoaciduria, glycosuria, and hyperphosphaturia (a Fanconi-like syndrome) which appears to be reversible.1 However, continued or repetitive exposures can cause a toxic stress on the kidney which, if untreated, may develop into chronic and often irreversible lead nephropathy (i.e., chronic interstitial nephritis).
In children, the acute lead-induced renal effects appear to be reversible with recovery usually occurring within two months of treatment.4
What Are the Symptoms of Kidney Disease?
In the beginning stages of kidney disease, there may not be many detectable symptoms. Therefore, children and adults who have been exposed to low levels of lead may not know whether they have some degree of kidney damage. When symptoms of kidney damage do occur, they may include significantly decreased urine production, swelling in the lower legs and ankles, hypertension, loss of appetite, muscle cramps, fatigue, digestive upset, and dry, itchy skin.
Are Renal Effects Easy to Detect?
Renal disease can be asymptomatic until the late stages and may not be detected unless tests are performed.
It should be noted that lead-induced end-stage renal disease is a relatively rare occurrence in the U.S. population.
Latent effects of lead exposure that occurred years earlier in childhood may cause chronic advanced renal disease or a gradual decrease in renal function.
Since excessive lead exposure in the past or the present may also be a causative agent in kidney disease associated with essential hypertension,1 Primary care providers should therefore follow closely the renal function of patients with hypertension and a history of lead exposure.
Are There Other Symptoms of Renal Disease?
Lead exposure is also believed to contribute to “saturnine gout,” which may develop because of lead-induced hyperuricemia due to decreased renal excretion of uric acid. In one study, more than 50% of patients suffering from lead nephropathy also suffered from gout.1
Lead-associated gout may occur in pre-menopausal women even though non lead-associated gout is uncommon in this population.5
- Lead Toxicity: What Are the Physiologic Effects of Lead Exposure? Agency for Toxic Substances and Disease Registry, August 20, 2007
- Lead and Compounds / Lippmann’s Environmental Toxicants: Human Exposures and Their Health Effects (3rd ed.), Grant, Wiley-Interscience, 2009
- Grant (2000), p. 789
- Lead Toxicity: What Are the Physiologic Effects of Lead Exposure? Agency for Toxic Substances and Disease Registry, August 20, 2007 (citing Chisolm et al. 1976)
- Lead Toxicity: What Are the Physiologic Effects of Lead Exposure? Agency for Toxic Substances and Disease Registry, August 20, 2007 (citing Goyer, 1985)