One Year on Automated Peritoneal Dialysis (APD), Weak Legs and Trouble Climbing Stairs: Causes to Check, How Much Protein, and Safe Leg Exercises

From our reader group: about one year on a cycler, but the legs feel weak

A member of a peritoneal dialysis support group, in their thirties, switched from hemodialysis through an arm access to automated peritoneal dialysis about a year ago.
Lately their legs feel weak, stepping up onto a ledge or climbing stairs is hard, and they asked how to get their strength back. Another member suggested focusing on protein.

Short answer: protein matters, but this symptom usually has several overlapping causes. Blood tests can find the fixable ones, and food and leg training work best together.
Eating more protein without using the muscles, or training hard without eating enough, rarely works. If you want to understand your lab report first, read
Reading Lab Results on Peritoneal Dialysis: BUN, Creatinine, eGFR, Low Potassium and TCO2

1. Why do legs get weak after some time on peritoneal dialysis?

Direct answer: people on peritoneal dialysis lose muscle through several routes at once: protein leaks into the dialysate, a full abdomen reduces appetite, uremic toxins and inflammation speed up muscle breakdown, and daily activity falls.
(Hu 2025)
The front thigh muscles do most of the work of rising from a chair and stepping up, so trouble with stairs is often the first sign.

How common is sarcopenia among Thai dialysis patients?

A study of 384 Thai peritoneal dialysis patients with a median age of about 60 found sarcopenia in 8.3% to 44.5%, depending on the definition used; by Asian criteria it was 22.3%.
Low muscle strength was found in 58.6% and low physical performance in 64.6%. Functional limitation affected 27.1% of those with sarcopenia versus 15.7% of those without.
(Meenetkum 2025)
These numbers show that loss of strength is more common than loss of muscle mass, and it occurs even in people who are not elderly.

How much protein leaks into the dialysate each day?

The capillaries of the peritoneal membrane let protein pass into the dialysate with every cycle. A study of 711 peritoneal dialysis patients found an average of 6.4 g of protein in the dialysate per day.
(Lu 2019)
A classic study measured about 8.8 g per day on manual continuous ambulatory peritoneal dialysis, and losses rose sharply during peritonitis.
(Blumenkrantz 1981)
About 3.4 g of free amino acids is also lost each day, an amount food can replace.
(Kopple 1982)

Target calculated from 1.0–1.2 g/kg/day per KDOQI 2020; losses from Lu 2019 and Kopple 1982

Low potassium is common on peritoneal dialysis

Peritoneal dialysis fluid contains no potassium, so daily exchanges keep removing it, while low intake and glucose from the dialysate push potassium into cells.
A review of 24 studies with 60,313 patients found potassium below 3.5 in about 17.7%. Low potassium was linked to about 1.49 times higher mortality and about 1.42 times more peritonitis.
(Yang 2024)
Mildly low potassium usually causes tiredness or cramps; weakness severe enough to stop walking usually appears when it is very low, around 2.5 or below, which needs urgent treatment.
(Kim 2023)

From Yang 2024: meta-analysis of 24 studies; units are mmol/L

High PTH and low vitamin D

Secondary hyperparathyroidism from kidney disease and vitamin D deficiency are linked to weakness of the thigh and hip muscles, together with bone pain.
Muscle weakness in chronic kidney disease has several mechanisms, including uremic toxins, oxidative stress and inactivity.
(Kaltsatou 2015)
Calcium, phosphorus, PTH and vitamin D belong in the work-up, but evidence that correcting these values alone improves leg strength is limited.

Anemia

Failing kidneys make less of the hormone that drives red blood cell production. Low hemoglobin means less oxygen reaches the muscles, so the legs tire quickly on stairs.
It is checked with hemoglobin, ferritin and transferrin saturation.

Is the dialysis enough, and how much do your own kidneys still work?

In the first years of dialysis, the remaining kidney function still clears waste and makes urine. As it declines, the original prescription may no longer be enough, and retained waste reduces appetite and increases muscle breakdown.
The ISPD 2020 recommendations set dialysis goals around symptoms, quality of life and nutrition, not just the Kt/V number.
(Brown 2020)

Other causes to consider

Peripheral neuropathy from diabetes or uremia, fluid overload and reduced heart function, some medicines such as corticosteroids and statins (uncommon, but they can cause muscle pain),
thyroid disorders, and depression or poor sleep. Frailty in dialysis patients therefore needs several kinds of care at once: diet, exercise, medication review and dialysis adjustment.
(Chan 2024)

Table: causes of leg weakness on peritoneal dialysis and the tests that separate them

Use this to prepare questions for your kidney team; more than one cause is usually present

2. Protein and energy: how much to eat on peritoneal dialysis

Direct answer: the KDOQI 2020 guideline recommends 1.0–1.2 g of protein per kg per day and 25–35 kcal per kg per day for metabolically stable people on dialysis.
(Ikizler 2020)
A 60 kg person therefore needs about 60–72 g of protein a day, more than before dialysis, when protein is usually restricted.

Why protein needs rise after starting dialysis

Before dialysis, limiting protein reduces the waste the kidneys must clear. Once dialysis starts, the fluid clears that waste, but it also removes protein and amino acids every day.
The protein target therefore goes up. A dietitian may set it higher during peritonitis or when protein-energy wasting is present.
Protein-energy wasting in kidney disease is diagnosed from several areas together: blood tests, body weight, muscle mass and how much food is eaten.
(Fouque 2008)

Energy matters as much as protein

If energy from food is too low, the body burns protein as fuel instead of building muscle. Some glucose is absorbed from the dialysate, and dietitians count it toward energy intake.
If the dialysate makes you feel full, try 5–6 small meals and eat main meals when there is less fluid in the abdomen.

Protein sources suited to people on dialysis

• Egg whites: high-quality protein with little phosphorus; whole eggs as your dietitian advises
• Fish and skinless chicken: good protein; boil, steam or bake
• Tofu: can alternate with meat, but ask about your own potassium and phosphorus limits
• Limit processed meats: sausages, ham and meatballs are high in salt and added phosphate

Do protein supplements help?

In a trial of 28 peritoneal dialysis patients given an egg-albumin protein supplement for 6 months, protein intake rose from 1.0 to 1.7 g per kg per day and albumin rose from 2.64 to 3.05.
(González-Espinoza 2005)
The trial was small and measured blood values, not leg strength. Supplements suit people who cannot reach the target with ordinary food, and a dialysis-specific formula should be chosen with a dietitian.

Table: nutrition targets before dialysis vs on peritoneal dialysis

Based on KDOQI 2020 for metabolically stable adults; your own numbers should be set by a renal dietitian

3. How to train your leg muscles safely with a PD catheter

Direct answer: a trial in peritoneal dialysis patients found that 12 weeks of home walking plus resistance training improved walking distance and quality of life, with no exercise-related adverse events.
(Uchiyama 2019)
Effective programs combine endurance and strength work, not a single exercise.

What the research shows

In a randomized trial of 47 peritoneal dialysis patients, those who did aerobic exercise 3 days a week and resistance training 2 days a week for 12 weeks walked farther on testing than controls,
and their albumin stayed stable.
(Uchiyama 2019)
A meta-analysis of 27 trials with 1,156 dialysis patients found exercise improved six-minute walk distance, sit-to-stand performance, grip strength and stair climbing.
(Clarkson 2019)
A Cochrane review of 45 trials with 1,863 people with chronic kidney disease also found benefits for fitness, walking and quality of life.
(Heiwe 2011)

Precautions from the ISPD recommendations

The International Society for Peritoneal Dialysis and the Global Renal Exercise Network recommend regular exercise for people on peritoneal dialysis, with attention to the catheter exit site, intra-abdominal pressure and hernias.
(Bennett 2022)
Most recommendations are expert consensus, so adapt them to the individual.

• If a full abdomen feels tight, exercise after draining or when the fill volume is low. Many cycler users have an empty or low-volume abdomen during the day, which suits training.
• Breathe out during effort. Do not hold your breath and strain, because straining raises intra-abdominal pressure.
• Ask your kidney team before heavy core work or heavy lifting, especially if you have had a hernia or a fluid leak.
• Secure the catheter before training and care for the exit site after sweating, drying it the way your dialysis unit taught you.
• Stop and contact your kidney team if you have chest pain, light-headedness, palpitations, abdominal pain, a bulge at the navel or groin, or fluid leaking around the catheter.

A progressive 12-week plan

5 leg exercises you can do at home

• Chair sit-to-stand: the key exercise, using the same muscles as stair climbing. Start from a high chair with hand support, then gradually use your hands less.
• Seated knee extension: sit upright, straighten one leg, hold 3–5 seconds and lower; 10 times per leg. Add an ankle weight when it becomes easy.
• Heel raises: stand holding a chair back, rise slowly onto your toes and lower, 10–15 times, for calf strength and balance.
• Step-ups: holding a rail, step up one stair with the stronger leg first, then switch; start with 5 per leg.
• Walking: at a pace where you can talk in sentences but not sing; add a few minutes each week.

Test yourself with the 30-second sit-to-stand

Sit on a chair without wheels, cross your arms, then stand up fully and sit down as many times as you comfortably can in 30 seconds. Record the number and repeat every 4 weeks.
If you cannot rise without your hands, note that and tell your kidney team. The number shows your progress and helps a physiotherapist tailor the program.

4. Options for managing leg weakness on peritoneal dialysis

Direct answer: what works is fixing the causes that tests find, together with food that meets the target and muscle training. The kidney team, a dietitian and a physiotherapist should plan this together.
(Chan 2024)

Table: comparing management options

Generic drug names only; all medicines and supplements must be supervised by your kidney team

Questions to ask your kidney team at the next visit

• What were my latest potassium, albumin, hemoglobin, calcium, phosphorus and PTH results?
• Does my falling urine volume mean my own kidney function is declining, and should the dialysis change?
• What are my daily protein and energy targets, and can I see a dietitian?
• Which exercises can I do, should I drain first, and can I be referred to a physiotherapist?
• Could any of my current medicines cause muscle weakness or pain?

Common beliefs vs the evidence

The more protein I eat, the faster my muscles come back

Protein above the target does not turn into muscle; it adds phosphorus and waste. Muscle needs enough protein, enough energy and actual use.

Egg whites alone are enough

Egg whites are good protein, but if total energy is too low the body burns protein as fuel. Eat several protein sources alongside suitable rice and fats.

Weak legs mean I should eat bananas or oranges right away

Add potassium only when the blood level is low. High potassium also causes weakness and dangerous heart rhythms. Check your blood result and follow the kidney team first.

Weakness on dialysis means I should rest as much as possible

Long bed rest makes muscles waste faster. Gradually increasing activity restores strength better, except during fever, infection or any symptom in the warning-signs section.

If my Kt/V meets the target, my dialysis is adequate

The ISPD 2020 recommendations also look at symptoms, appetite, nutrition and quality of life. If appetite and strength are falling, discuss adjusting dialysis even when the number meets the target.

Frequently Asked Questions (FAQ)

Why are my legs weak and stairs hard after about a year on APD?

Several causes usually combine: muscle loss from too little protein and energy, protein leaking into the dialysate, low activity, low potassium, anemia, and high PTH or low vitamin D. In the first year your own kidney function may also decline so the original prescription is no longer enough. A study of Thai peritoneal dialysis patients found low muscle strength in 58.6%.

How much protein does peritoneal dialysis fluid remove each day?

A study of 711 peritoneal dialysis patients found an average of 6.4 g per day; a classic study measured about 8.8 g per day, plus about 3.4 g of free amino acids. Losses rise sharply during peritonitis. Food that meets the target can replace this amount.

How much protein should I eat on peritoneal dialysis?

The KDOQI 2020 guideline recommends 1.0–1.2 g per kg per day for metabolically stable people, with 25–35 kcal per kg per day. A 60 kg person needs about 60–72 g of protein a day, more than before dialysis. A dietitian may raise it during infection.

Can low potassium cause leg weakness, and should I eat more fruit on my own?

Yes. About 17.7% of peritoneal dialysis patients have low potassium, and clear weakness usually appears when it is very low, around 2.5 or below. Do not add potassium without a blood test, because high potassium is also dangerous. The Thai trial used prescribed potassium chloride with blood monitoring.

How are high PTH and low vitamin D linked to leg weakness?

Secondary hyperparathyroidism and vitamin D deficiency are linked to weak thigh and hip muscles with bone pain, so calcium, phosphorus, PTH and vitamin D should be checked. Evidence that correcting these alone improves leg strength is limited, so combine it with diet and training.

Which leg exercises are safe with a peritoneal dialysis catheter?

Chair sit-to-stands, seated knee extensions, heel raises, step-ups holding a rail, and walking. Train when the abdomen holds less fluid if it feels tight, breathe out during effort and do not strain. Ask your kidney team before heavy core work or heavy lifting, and care for the exit site after sweating.

Which tests should I ask for when my legs are weak?

Potassium, albumin, hemoglobin, iron studies, calcium, phosphorus, PTH, vitamin D, HbA1c if you have diabetes, dialysis adequacy and daily urine volume, together with a nutrition assessment and a sit-to-stand test. If muscle pain started after a new medicine, the doctor may also check CK.

How long until my legs get stronger?

Trials in peritoneal dialysis patients showed walking improvements after 12 weeks of training. Strength usually improves gradually over weeks to months, depending on whether other causes are corrected. A 30-second sit-to-stand test every 4 weeks helps you see progress.

Scientific Mechanism

Muscle protein balance: muscle constantly builds and breaks down protein. In chronic kidney disease, uremic toxins, inflammation, metabolic acidosis and insulin resistance
activate protein-breakdown pathways in muscle cells, while synthesis falls when amino acids and energy are short or the muscle is not used. The net result is muscle wasting and lost strength.
(Hu 2025,
Kaltsatou 2015)

Protein leakage across the peritoneum: peritoneal capillaries contain a small number of large pores that let proteins such as albumin pass into the dialysate.
People with high protein loss often have inflammation or vascular abnormalities and higher mortality; each 10 mL/day increase in peritoneal protein clearance was linked to about 10.4% higher mortality.
(Guedes 2019,
Lu 2019)

Potassium and muscle function: muscles contract when an electrical signal travels along the cell membrane. Low extracellular potassium moves the membrane potential further from its firing threshold,
so muscles respond sluggishly and weakly, and heart rhythm can become irregular. A Thai trial found that keeping potassium at 4–5 lowered peritonitis risk (HR 0.47),
possibly through better bowel motility.
(Pichitporn 2022)

Resistance training: mechanical tension during training switches on protein-building signals in muscle cells. With amino acids available from food, synthesis can exceed breakdown.
Training and food therefore have to go together; either one alone does less.

Compiled and reviewed by Asst. Prof. Dr. Norawit Raatpiboon

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