Dialysis frequently makes people feel cold, and the sensation is not imagined. Up to 70% of patients undergoing in-center hemodialysis with cooled dialysate report feeling cold during treatment, with some experiencing outright shivering.1PubMed Central. Cooling dialysate during in-center hemodialysis: Beneficial and deleterious effects The reasons go well beyond a drafty clinic room. Your blood is circulating outside your body through tubing and a filter, the fluid washing against that blood is often deliberately cooled, your baseline body temperature may already run low, and the access site on your arm can redirect blood flow away from your hand. Each of these factors stacks on the others, which is why the cold feeling during dialysis can be so persistent and hard to shake.
How Blood Circulating Outside the Body Pulls Heat Away
During hemodialysis, blood travels from your body through plastic tubing, passes through a dialyzer where waste is filtered out, and returns. While outside the body, that blood is in close thermal contact with dialysate, the cleansing fluid running on the other side of the dialyzer membrane. If the dialysate is cooler than your blood, heat flows from blood to fluid, and you lose thermal energy with every pass through the circuit. Researchers have measured this energy transfer continuously during sessions by tracking the temperature difference between the blood leaving and returning to the patient.2American Journal of Kidney Diseases. Effect of dialysate temperature on energy balance during hemodialysis: Quantification of extracorporeal energy transfer Because a hemodialysis session typically runs three to four hours, even a small temperature gap between your blood and the dialysate adds up to meaningful heat loss over time.
This is not an accident. Clinicians often set the dialysate temperature a degree or more below normal body temperature on purpose. Cooler dialysate helps blood vessels stay constricted, which supports blood pressure during the large fluid shifts that happen as excess water is pulled from your blood. The trade-off is that you feel cold. When dialysate was kept at standard body temperature in one crossover study, patients’ core temperature actually crept upward during treatment, while cooled dialysate kept core temperature stable but shifted patients’ thermal perception toward cold.3PubMed. Physical intradialytic patient-reported outcome measures in haemodialysis and haemodiafiltration: A cross-over study In plain terms, the cooling works for blood pressure but the price is comfort.
Why Dialysis Patients Often Run Cool Even Before Treatment Starts
Many people on long-term hemodialysis have a resting body temperature that sits below the textbook figure of 37 °C. A retrospective study of 75 hemodialysis patients found that the average pre-dialysis oral temperature was already lower than 37 °C.4American Journal of Kidney Diseases. Body temperature regulation during hemodialysis in long-term patients: is it time to change dialysate temperature prescription? This matters because dialysate temperature is often set with 37 °C in mind. If your baseline is already 36.2 or 36.4 °C, a dialysate temperature of 36.5 °C may actually be close to your core temperature and cause less chilling. But a one-size-fits-all dialysate prescription of, say, 35.5 °C could amount to a full degree below your starting point, pulling out considerably more heat than intended.
Why the low baseline? Advanced kidney disease disrupts many systems that regulate body temperature. Metabolism slows, thyroid hormone levels often dip, and the body’s thermoregulatory set point can shift downward. Patients report becoming more sensitive to cold in daily life, well outside the dialysis clinic, after developing kidney failure. In a qualitative study, participants described feeling cold in their hands and feet as a new experience that arrived alongside their diagnosis, one they had never dealt with before.5PubMed Central. The Experience of “Feeling Cold” in Patients Undergoing In-Centre Haemodialysis They described needing extra layers of clothing and blankets as a permanent adjustment, not just during treatment.
The Access Site Can Make One Hand Noticeably Colder
Hemodialysis requires a vascular access point, usually an arteriovenous fistula or graft surgically created in the arm. These connections reroute some arterial blood directly into a vein, bypassing the small vessels that normally feed the hand and fingers. When the diverted blood flow is large enough, the tissue downstream can become starved, a condition called steal syndrome. The hallmark complaint is a cold hand on the access side.
How common is it? In one study comparing different access types, a cold hand was present in half of patients with an upper-arm fistula, compared with about a quarter of those with prosthetic forearm loops and roughly one in eight with a wrist-level fistula.6European Journal of Vascular and Endovascular Surgery. Steal in Hemodialysis Patients Depends on Type of Vascular Access Digital skin temperatures and grip strength were measurably lower in affected hands. When the fistula was temporarily compressed by hand, blood pressure in the fingers jumped back to normal, confirming that the access was stealing the flow. A separate study found that steal syndrome was significantly more common with grafts than with fistulas overall.7PubMed Central. Incidence of steal syndrome following arteriovenous fistula and arteriovenous graft
Steal syndrome ranges from mild coldness and tingling to, in rare cases, tissue damage. If the hand on your access side is persistently cold, pale, or numb, that is worth raising with your care team. Mild cases may just need monitoring. More severe cases can be addressed surgically by modifying blood flow through the access.
Autonomic Dysfunction and Diabetes
Your nervous system normally responds to cooling by constricting blood vessels in the skin and shunting blood toward the core to conserve heat. In people with advanced kidney disease, this reflex is often blunted, and diabetes makes it worse. A study comparing diabetic and non-diabetic hemodialysis patients found that diabetic patients had reduced overall autonomic nervous system activity and a blunted response to the stress of dialysis, while non-diabetic patients showed a normal increase in cardiac sympathetic activity during treatment.8Kidney and Blood Pressure Research. Effect of Dialysate Temperature and Diabetes on Autonomic Cardiovascular Regulation during Hemodialysis In practical terms, a non-diabetic patient might feel chilly during dialysis but still mount an adequate warming response. A diabetic patient’s body may be slower to react, letting core and skin temperature drop further before compensation kicks in.
This compounds the problems already discussed. If your thermostat is sluggish, cooled dialysate pulls heat out faster than your body can generate it or redirect it. The result is deeper and longer-lasting cold sensations, and potentially greater blood pressure instability on top of them.
Thyroid Problems That Hide Behind Kidney Disease
Hypothyroidism, an underactive thyroid, is a classic cause of cold intolerance. It is also strikingly common in people with advanced kidney disease, and it often goes undiagnosed because the symptoms overlap almost perfectly with uremia: fatigue, cold intolerance, mental fogginess, and sluggishness.9PubMed Central. The Interaction Between Thyroid and Kidney Disease: An Overview of the Evidence If you have been on dialysis for a while and assume that feeling cold is just part of the package, it is worth asking whether your thyroid levels have been checked recently. Treating hypothyroidism with thyroid hormone replacement will not make dialysis warmer, but it can address a separate contributor to your overall cold sensitivity.
When You Dialyze Matters More Than You Might Think
Your body temperature is not constant throughout the day. It follows a circadian rhythm, peaking in the late afternoon and bottoming out in the early morning hours. This daily temperature cycle does not disappear in dialysis patients, and it turns out to have real implications for how cold a session feels. A study tracking temperature in patients across different dialysis shifts found that both the starting temperature and the change in temperature during treatment were significantly related to the time of day.10PubMed. Circadian variations in body temperature during dialysis If you dialyze in the morning when your body is still near its temperature low point, you start cooler and lose heat faster. An afternoon session, when your core temperature is closer to its peak, may begin from a warmer baseline and feel less frigid.
The researchers also connected these temperature swings to blood pressure changes during dialysis. Because lower body temperature can mean less vascular tone, an early-morning session with its naturally cooler starting point may compound the risk of blood pressure drops. This is an area where scheduling flexibility, where it exists, could make a tangible difference in comfort.
The Room Itself
Dialysis clinics face a peculiar climate dilemma. Patients sit still for hours, often with bare arms connected to tubing, while staff move around the unit performing physical tasks. A field survey of dialysis rooms during autumn and winter found that air temperatures fluctuated between about 21.6 °C and 27.1 °C depending on the season and time of day, with relative humidity below 50% and very little air movement.1110th International Conference on Healthy Buildings 2012. A Study of Thermal Comfort Reported by Patients and Medical Staff in a Dialysis Room during Autumn and Winter What feels comfortable for a nurse walking between stations can feel uncomfortably cool for a sedentary patient who is simultaneously losing heat through an extracorporeal circuit.
There has been some discussion in the nephrology sustainability literature about lowering dialysis room temperatures to reduce energy consumption. A Swiss working group on sustainable nephrology acknowledged that dropping the room from 24 °C to 21 °C could save energy, but cautioned that patient comfort, especially for older patients, would likely suffer, and the reduction is not generally recommended.12Clinical Kidney Journal. Ten tips from the Swiss Working Group on Sustainable Nephrology on how to go green in your dialysis unit For patients already chilled by cool dialysate, a few extra degrees of room warmth or a heated blanket can take some of the edge off.
Eating During Treatment and Blood Pressure Drops
Some patients eat during dialysis, especially during long sessions. Eating diverts blood flow to the digestive organs, which can reduce resistance in peripheral blood vessels and cause a temporary dip in blood pressure.13Journal of Renal Nutrition. Eating During Hemodialysis Treatment: On the Arguments For and Against and the Need for a Better Evidence Base While this is primarily a blood pressure concern rather than a temperature issue, the two are linked. When blood pressure drops, the body compensates by constricting skin blood vessels to protect the core, and the outward sign of that constriction is cold, pale skin and extremities. If you already feel cold during dialysis and notice it gets worse after eating, the post-meal blood pressure dip may be amplifying your chill.
Isothermic Dialysis and Biofeedback Technology
The blunt-instrument approach to dialysis cooling is to set the dialysate at a fixed low temperature for everyone. A more refined method is isothermic dialysis, where the machine automatically adjusts the dialysate temperature to keep your core body temperature from changing during the session. Temperature sensors in the blood lines measure the warmth of blood leaving and returning, and a controller tweaks the dialysate in real time to maintain a target.
A European randomized trial compared isothermic dialysis to thermoneutral dialysis (where the machine aims for zero net heat transfer). Isothermic dialysis required a mean dialysate temperature of about 35.7 °C, meaningfully lower than the 37.5 °C used in the thermoneutral arm. Yet the isothermic approach cut episodes of blood pressure drops roughly in half, and, importantly, no patients reported unpleasant cold symptoms or shivering.14PubMed Central. Feedback control in hemodialysis The reason appears to be that the cooling is calibrated to each person’s physiology rather than applied as a flat reduction. A blood temperature monitor can deliver hemodynamic stability without the brute discomfort of a one-size-fits-all cool setting.15PubMed. Temperature control by the blood temperature monitor
Not every dialysis unit has biofeedback-equipped machines. Where the technology is available, it is worth asking about. Where it is not, even a modest personalization of dialysate temperature, adjusting by half a degree based on your measured pre-dialysis temperature rather than using a clinic-wide default, can help.
What You Can Do About It
If cold during dialysis is making your sessions miserable, here are some practical angles to discuss with your care team and try on your own:
- Dialysate temperature review: Ask whether your dialysate temperature has been individualized. If your baseline body temperature runs low, a standard “cool” prescription may be overshooting. Even a small upward adjustment can reduce discomfort without necessarily sacrificing blood pressure stability.
- Warm clothing and blankets: This sounds obvious, but layering matters. Warm socks, a hat, a fleece blanket, and even hand warmers can offset peripheral heat loss. Some clinics stock heated blankets.
- Session timing: If your schedule allows, an afternoon slot may feel less cold because of your body’s natural temperature peak.
- Thyroid screening: If you haven’t had thyroid function checked recently, ask for it. Treating a thyroid deficit will not fix dialysis-related cooling but it addresses one overlapping cause of cold intolerance.
- Access-side hand coldness: If one hand is consistently colder than the other, especially on the arm with your fistula or graft, mention it specifically. Steal syndrome is identifiable and, when needed, treatable.
- Biofeedback machines: If your clinic has blood temperature monitoring capability, ask whether isothermic dialysis is an option. The evidence suggests it preserves the blood pressure benefits of cooling without the worst of the cold discomfort.
Home Dialysis and Peritoneal Dialysis
Most of the research on feeling cold during dialysis focuses on in-center hemodialysis, where blood travels through an external circuit and the dialysate temperature is set by staff. If you do home hemodialysis, you have direct control over the dialysate temperature and can experiment within the range your nephrologist recommends. Some home patients find that setting the dialysate closer to their own body temperature (measured just before the session) reduces chilling enough to make treatment more tolerable, even if it means slightly less blood-pressure protection.
Peritoneal dialysis works differently. Instead of blood passing through tubing, dialysate is infused into your abdominal cavity and drained periodically. The fluid warms to body temperature after it enters the peritoneum, so the sustained heat loss through an extracorporeal circuit does not apply. Peritoneal dialysis patients can still feel cold for the same baseline reasons, low resting temperature, hypothyroidism, and autonomic issues, but the treatment itself is less likely to actively chill them the way hemodialysis does. For people who find the cold intolerable and are candidates for peritoneal dialysis, modality choice is a conversation worth having with their care team.