Plasma donation, formally known as plasmapheresis, involves drawing blood, separating the liquid plasma component, and returning the remaining red blood cells to the donor. This common medical procedure provides raw material for life-saving therapies. Kidney stones are mineral and salt deposits that form inside the kidneys, affecting about one in ten people. Given the body’s temporary physiological changes during donation, many people question whether routinely donating plasma increases the long-term risk of developing these stones.
Scientific Consensus on Plasma Donation and Stone Risk
Current large-scale data and epidemiological studies do not establish a direct causal link between routine plasma donation and the chronic formation of kidney stones. While plasmapheresis involves temporary changes to the body’s fluid balance and chemistry, these alterations are not sufficient to initiate stone crystallization in a healthy individual.
Kidney stone formation is primarily linked to persistent metabolic conditions, chronic dehydration, and dietary factors that lead to an oversaturation of stone-forming substances in the urine. Chronic risk factors like obesity, diabetes, and a family history of stones play a much larger role in a person’s risk profile. The temporary nature of the physiological shifts during donation means the body quickly restores normal balance shortly after the procedure.
If plasma donation were a significant, independent risk factor for chronic stone disease, a pattern would be apparent in the long-term health records of frequent donors. The absence of such a pattern in the scientific literature suggests the procedure itself is not a major contributor to chronic stone formation.
Physiological Factors During Donation That Raise Concern
Concerns about kidney stone risk arise from two specific, temporary physiological effects during the donation process.
Fluid Volume Removal
The first concern is the temporary, but substantial, removal of fluid volume, since plasma is about 92% water. If a donor is already dehydrated before the procedure, the further loss of plasma volume can concentrate the remaining blood and the urine. Highly concentrated urine is a known risk factor for stone formation because it increases the saturation of minerals like calcium and oxalate. This is a behavioral risk, not an inherent risk of the donation process itself, since proper pre-hydration is part of the required protocol.
Citrate Use
The second factor is the use of citrate, an anticoagulant added to the drawn blood to prevent clotting in the machine’s external tubing. Citrate works by binding to calcium in the bloodstream, causing a temporary reduction in ionized calcium (hypocalcemia). This temporary drop in calcium causes the tingling sensation often felt during donation. Citrate is a highly effective natural inhibitor of kidney stones and is sometimes prescribed therapeutically for stone formers. While the citrate used during donation is metabolized quickly, the short-lived systemic effect of calcium binding does not translate into increased calcium oxalate deposition within the kidneys.
Maintaining Kidney Health While Donating Plasma
Maintaining optimal kidney health while donating plasma centers heavily on proactive hydration management. Since plasma is mostly water, donors should aim to increase their fluid intake significantly in the 24 hours leading up to their appointment. A good guideline is to drink several extra glasses of water beyond the typical daily recommendation.
Avoid beverages that promote dehydration, such as excessive amounts of caffeine and alcohol, especially in the hours immediately before a donation. Monitoring urine color serves as a simple indicator of hydration status; pale yellow or straw-colored urine suggests adequate hydration, while dark yellow urine suggests a need for more fluids.
Donors should also focus on maintaining a balanced diet, which is a general recommendation for preventing kidney stones. Moderation of high-oxalate foods like spinach and nuts can be beneficial for those susceptible to calcium oxalate stones. Anyone with a personal history of kidney stones or a strong family history should consult with their doctor before starting or continuing a plasma donation schedule.