Porphyria Cutanea Tarda No Longer Common in Kidney Disease Patients
Drop in once common comorbidity for ESRD due to 'modern hemodialysis era'
Porphyria cutanea tarda (PCT), the most common form of porphyria, is much less common among people with kidney disease today than it has been in the past, a recent study suggests.
“This study shows, for the first time, that in modern hemodialysis era, possibly due to improved porphyrins’ metabolism and dialysis removal, PCT is much less prevalent than previously reported,” the researchers wrote.
The study, “Plasma porphyrins among end stage renal disease patients and cutaneous symptoms — is there still an association?,” was published in the journal Molecular Genetics and Metabolism Reports.
Like other types of porphyria, PCT is characterized by the buildup of heme precursors and intermediate molecules called porphyrins. Of note, heme is a molecule that plays a key role in oxygen transport in living cells. PCT specifically is caused by the lack of function of an enzyme called uroporphyrinogen decarboxylase, or UROD, which is involved in the production of heme.
Porphyria and ESRD rates ranged between 5% and 18% in previous century
Multiple studies done in the previous century found PCT to be common among patients with kidney disease. Rates of PCT ranging between 5% and 18% were reported among individuals with end stage renal disease (ESRD), a condition where the kidneys cannot function properly and fail to meet the body’s needs, causing patients to go on long-term dialysis or undergo a kidney transplant. Skin-related porphyria symptoms were particularly common among ESRD patients.
In the decades since these studies were done, there have been substantial improvements in the care of people with ESRD, such as the development of better dialysis systems. Theoretically, these improvements might be expected to reduce the risk of complications like PCT, but studies are lacking into the prevalence of PCT among ESRD patients receiving modern treatment.
To fill in this knowledge gap, a team of scientists in Israel investigated 94 people undergoing dialysis for ESRD.
“The correlation between ESRD and PCT has been evaluated and published during the middle and late decades of the previous century. Since [then], treatment of ESRD patients have dramatically changed for the better,” the researchers wrote. “However, PCT is still quoted as a common co-morbidity [co-occurring condition] in ESRD patients.”
About one-third (30.1%) of the patients in this study were female. Patients had a mean age of 67.8 and had remained on dialysis for a median of nearly five years.
All of the patients underwent detailed skin examinations and blood tests. They were also asked to complete the Dermatology Life Quality Index (DLQI) — a standardized questionnaire to evaluate skin symptoms and their impact on the quality of life.
Based on the evaluations, none of the 94 patients were diagnosed with PCT. None showed common PCT skin symptoms, like ulcers or large blisters.
While this result reflects a limited number of patients at a single center, the researchers noted that “even if PCT is still occasionally relevant in ESRD,” this group of patients “is sufficient to demonstrate PCT is not as common as previously described.”
In a few patients (24.5%), total porphyrin levels were slightly higher than normal. However, porphyrin levels showed no clear association with any measure of kidney function. Porphyrin levels also showed no association with skin changes that might theoretically be due to PCT, such as scarring or sun sensitivity, or with skin-related symptoms as measured by DLQI scores.
Researchers noted that patients with elevated porphyrin levels tended to be younger than those whose levels fell within the normal range (mean age of 58.9 vs. 70.7).
“This finding may be due to porphyrin metabolism changes with age, however it is beyond the scope of this study, and should further be evaluated in future studies,” the scientists wrote.