A University of Washington (UW) study strongly associates the injection of “black tar” heroin with an untreatable kidney disease that often leads to dialysis and death.
The paper, published June 15 in the Clinical Journal of the American Society of Nephrology, showed that, among 38 patients diagnosed with AA-type kidney amyloidosis, 95 percent had a prior history of heroin use. Black tar heroin is a dark, sticky, drug substance popular in the Pacific Northwest.
AA-type amyloidosis is rare and historically associated with chronic autoimmune or inflammatory conditions such as rheumatoid arthritis, lupus and inflammatory bowel disease.
“But in certain geographic areas, like Seattle, most of the people who had this unusual condition were chronic heroin users,” said lead author Dr. Bryan Kestenbaum, a professor of nephrology at the UW School of Medicine and adjunct professor of epidemiology at the University of Washington School of Public Health. He’s also an investigator at the Kidney Research Institute, a collaboration between Northwest Kidney Centers and UW Medicine.
Patients in the study had been evaluated or treated for kidney disease between 2005 and 2015 at Harborview and UW Medical Centers in Seattle, Washington. The control group included patients who had other kidney disorders but not AA-type amyloidosis. Among them, the percentage of past or present heroin use was 14 percent.
Amyloidosis stems from the body’s inability to process certain proteins, which in turn are deposited in the kidneys and other organs. Amyloid-filled kidneys lose their ability to filter wastes from the blood.
The use of black tar heroin causes scarring of regular injection sites, prompting users to inject the drug directly into their muscles, which may stimulate production of the amyloid protein. “Infections cause the body to produce many inflammatory proteins. One of these, called serum amyloid A, can be processed in an abnormal way, leading to AA-type amyloidosis,” Dr. Kestenbaum said.
No effective therapies exist for AA-type amyloidosis. This review of affected study patients showed that they rapidly progressed to dialysis dependence and death.
The study does not prove that black tar heroin causes amyloidosis, but this variety of the drug is thicker and less pure than the white-powder heroin more readily available in other geographic regions.
“If you use heroin in the Pacific Northwest, it is unlikely that you will develop this disease,” Dr. Kestenbaum said. “But this study indicates that such a user is more than 100 times more likely to develop the disease than an otherwise similar person who does not use heroin.”