Children and kidney disease are a serious issue that could be becoming far more serious according to a new study. Small amounts of lead in the bodies of healthy children and teens — amounts well below the levels defined as “concerning” by the U.S. Centers for Disease Control and Prevention (CDC) — may worsen kidney function, according to a Johns Hopkins Children’s Center study published in the Jan. 11 issue of Archives of Internal Medicine.

In 1991, the CDC reduced the lead level “of concern” for children from 30 micrograms to 10 micrograms per deciliter of blood, but the Johns Hopkins findings suggest that even levels below 10 present a health risk, providing the first evidence that lead levels that low may impair kidney function.

“To our knowledge, this is the first study to show that very low levels of lead may impact kidney function in healthy children, which underscores the need to minimize sources of lead exposure,” says lead investigator Jeffrey Fadrowski, M.D. M.H.S., a pediatric nephrologist at Hopkins Children’s.

The Johns Hopkins team cautions that their findings present only a snapshot of kidney status and lead levels, and do not offer definitive proof of cause and effect between the two. But the scientists say their findings are worrisome and emphasize the urgent need for studies that track lead levels and kidney function over time to better understand the interplay between the two and limit lead’s bearing on the burgeoning connection between children and kidney disease.

“Our findings were particularly striking because we saw slightly decreased kidney function in healthy children without conditions that could account for it, and this could spell more kidney trouble down the road as these children get older or if they acquire additional risk factors for kidney disease, such as high blood pressure and diabetes,” says Susan Furth, M.D. Ph.D., senior investigator on the study and a pediatric nephrologist at Hopkins Children’s.

Of the 769 healthy children and teens in the study, ages 12 to 20, more than 99 percent had lead levels below 10, with an average level of 1.5 micrograms per deciliter. Those with lead levels in the upper quarter of the normal range appeared to have worse kidney function than children with lower lead levels. Kidney function is defined by the speed with which the kidneys filter the blood. Those with lead levels above 2.9 had a kidney filtration rate 6.6 units (milliliters of blood filtered per minute and adjusted for body size) lower than children whose lead levels were below 1 microgram per deciliter. Researchers also found that for each twofold increase in the amount of lead in the blood, the kidney’s filtration capacity dropped by 2.3 units in males and by 3.3 in females. The link between higher lead levels and worse kidney function persisted even after investigators eliminated high blood pressure — less than 5 percent of those in the study had it — as a possible factor affecting kidney status.

In the current study, the investigators measured kidney function by estimating the kidneys’ filtering capacity, called glomerular filtration rate (GFR), using two tests: a standard creatinine test, which measures the speed with which the kidneys filter out creatinine from the blood, and a newer test that measures how fast the kidneys filter out the protein cystatin C. Cystatin C is believed to be a more accurate gauge because, unlike creatinine, which can fluctuate depending on muscle mass and other factors, its levels are more stable. Indeed, the differences in kidney function were far more pronounced when the researchers looked at cystatin C and not as significant when they applied the standard creatinine test. The investigators say this could mean that past studies that have used creatinine tests may have underestimated the true effect of lead on kidney function.

Lead exposure is a well-established risk factor for neurological damage and developmental delays in children, while chronic exposure to high lead levels is a well-known cause of chronic kidney disease in adults. Despite the elimination of lead from gasoline and paint, most Americans still have detectable lead levels in the blood. The mean blood lead levels in the 12-to-19-year-olds were 1.5 micrograms per deciliter in 1991 to 1994 and 1.1 micrograms per deciliter from 1999 to 2000, researchers say.

Current Exposure Sources To Be Careful Of

• Lead paint, especially in old homes. Be sure to strip and repaint any surfaces containing lead paint, typically this is found in any buildings built before 1978. 

• Folk remedies (like Greta and Azarcon), these are just a few old remedies among many others which unfortunately utilize toxic amounts of lead. They should be avoided!

• Glazed pottery, especially older or antique pieces were probably glazed with lead-containing compounds meaning they are unsuitable for food preparation. Some will have warnings stamped on them by the manufacturer, but there are also lead-testing kits which you can use to determine if your pottery contains lead. 

• Soil should always have pH levels above 6.5 as this makes it unsuitable for lead. If you suspect high lead levels are an issue, there are tests you can purchase to have a more accurate view. You should never garden in lead-tainted soil.

• Drinking water in some urban areas with older housing. Be sure to check your water for lead, and if necessary, talk to your landlord or local health inspector to get the situation remedied as soon as possible. 

Chronic kidney disease affects 26 million people in the United States, many of them children. If you’d like to learn more about the various supplements, diets and other remedies which can help preserve kidney function, you need to check out our All-Natural Kidney Health & Kidney Function Restoration Program, available here!