A new study analyzing tens of thousands of people living with kidney disease from around the world shows they can have greatly varying levels of hemoglobin, a protein critical for transporting oxygen throughout the body. The results, published in Kidney International Reports, suggest doctors may need to rethink the way they approach treating low hemoglobin levels (anemia) in this population.
The kidneys are indirectly involved in the production of hemoglobin, and therefore it’s not uncommon that people living with kidney disease have lower hemoglobin levels compared to the general population.
“It is relatively common as a complication, especially as the kidney function gets quite low,” explains Dr. Mark Canney, an associate scientist in the Clinical Epidemiology Program at the Ottawa Hospital Research Institute.
In 2019, Canney was working as a research fellow with UBC’s Division of Nephrology when his supervisor, Dr. Adeera Levin, recommended launching an international effort to better understand hemoglobin variation among the kidney disease population.
They partnered with investigators around the world, analyzing more than 21 cohorts of adults and three cohorts of children with kidney disease whose hemoglobin levels had been collected through previous studies. Together, the data captured more than 58,600 people living with kidney disease across six continents.
The results show that female study participants generally have lower hemoglobin levels than their male counterparts. While these differences in hemoglobin between the sexes is known in people with healthy kidney function, this study shows the trend remains true even in people with low kidney function.
Canney notes this could mean that hemoglobin targets in females with kidney disease may not necessarily need to be the same as for males with kidney disease, although more research is needed to understand the underlying reasons for these differences.
The data also point to some regional differences in hemoglobin levels, with women in Africa and Asia tending to have lower levels compared to women in Europe.
However, the researchers found that even within groups of people based on sex, geographic location and cause of kidney disease, there continued to be wide variations in hemoglobin levels even at the same level of kidney function.
“To us, these results suggest we need to be thinking a little bit more outside of our kidney sphere,” says Canney, noting that other factors – such as diet, genetics or even local infection rates – could be contributing to the variation observed in this study. “Ultimately, it does beg the question whether we should be applying the same fairly narrow hemoglobin target to everybody living with kidney disease.”
Canney says the Canadian members of this team have created a great network of international collaborators through this work, and may conduct follow-up studies to better capture additional data that may explain the variation in hemoglobin levels.
