- Answer each of the five SARC-F items below from the patient's report — strength, walking assistance, rising from a chair, climbing stairs, and falls in the past year. Each scores 0, 1, or 2.
- The SARC-F total (0–10) updates live. A score of ≥ 4 is a positive screen suggestive of sarcopenia.
- Optionally enter sex and calf circumference (cm) to compute the more sensitive SARC-CalF. If calf circumference is below the sex cut-off (men < 34 cm, women < 33 cm), 10 points are added; SARC-CalF ≥ 11 is a positive screen.
- The result card shows the SARC-F score, the SARC-CalF score (when calf circumference is entered), and the overall screen result with a recommended action.
- A positive screen prompts confirmatory assessment of muscle strength, mass, and physical performance — it is a screen, not a diagnosis.
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When to Use
Use SARC-F (and SARC-CalF) as a rapid, low-burden first step to identify patients who should undergo formal sarcopenia assessment. Sarcopenia — loss of skeletal muscle mass and function — is highly prevalent in CKD and end-stage kidney disease, driven by protein-energy wasting, chronic inflammation, metabolic acidosis, uremia, physical inactivity, and the catabolic stress of dialysis. It independently predicts falls, hospitalization, impaired quality of life, and mortality. Both EWGSOP2 and AWGS recommend SARC-F (or SARC-CalF) as the recommended case-finding step before confirmatory testing.
Appropriate population
Older adults and any CKD, dialysis, or transplant patient at risk for protein-energy wasting or muscle loss — particularly those reporting weakness, slowness, recent falls, or unintentional weight loss. Useful at routine nutrition reviews, at dialysis initiation, and when assessing frailty or transplant candidacy. SARC-CalF (adding calf circumference) raises sensitivity over SARC-F alone and is preferred when a tape measure is available.
What it is — and is not
SARC-F is a screening tool, not a diagnostic test. A positive screen flags a patient for confirmatory assessment; it does not establish sarcopenia. A negative screen does not exclude it, especially in patients with edema or fluid overload, where calf circumference overestimates muscle. In dialysis patients, measure calf circumference on the non-fistula leg, ideally post-dialysis at dry weight, because interdialytic fluid inflates the reading and can mask low muscle mass.
Pearls & Pitfalls
Know the two cut-offs
SARC-F is positive at ≥ 4 of 10. SARC-CalF adds 10 points when calf circumference is below the sex cut-off (men < 34 cm, women < 33 cm), and is positive at ≥ 11 of 20. Adding the calf measurement raises sensitivity while keeping the questionnaire's speed and simplicity.
Measure calf circumference correctly
Measure the largest circumference of the non-dominant (or non-fistula) calf with the patient seated, knee and ankle at 90°, using a non-stretch tape without compressing the skin. In dialysis or fluid-overloaded patients, measure post-dialysis near dry weight — interdialytic edema inflates the reading and can falsely "pass" a patient with low muscle mass.
Pitfalls
(1) A positive screen is a trigger for assessment, not a diagnosis — confirm with strength, mass, and performance measures. (2) A negative screen does not exclude sarcopenia, especially with edema. (3) Calf circumference overestimates muscle in fluid overload. (4) SARC-F relies on self-report and may be confounded by pain, arthritis, neurologic disease, or dyspnea. (5) Calf-circumference cut-offs vary by population; the 34/33 cm thresholds are commonly used and align with Asian (AWGS) values.
Why Use It
Sarcopenia is common but under-recognized in CKD and dialysis, where protein-energy wasting and a catabolic milieu accelerate muscle loss. Because it independently predicts falls, fractures, hospitalization, and mortality, early case-finding lets clinicians intervene — optimizing protein and energy intake within CKD-appropriate targets, prescribing resistance exercise, and treating reversible contributors such as metabolic acidosis, inadequate dialysis, depression, and vitamin D deficiency. SARC-F takes under a minute, needs no equipment, and SARC-CalF adds only a tape measure, making structured screening feasible at every nutrition or dialysis review.
SARC-F & SARC-CalF Sarcopenia Screening Calculator
Answer the five SARC-F items to get the score and screen result. Calf circumference and sex are optional — add them to compute the more sensitive SARC-CalF.
SARC-F items
Optional — calf circumference (SARC-CalF)
⚕ SARC-F: five items (strength, assistance walking, rising from a chair, climbing stairs, falls), each 0–2; total 0–10; positive ≥ 4. SARC-CalF: SARC-F + 10 points if calf circumference is below the sex cut-off (men < 34 cm, women < 33 cm); total 0–20; positive ≥ 11. A screening tool, not a diagnosis — confirm with strength, mass, and performance measures per EWGSOP2/AWGS. Source: Malmstrom & Morley, J Am Med Dir Assoc 2013;14(8):531–532; Barbosa-Silva et al., J Am Med Dir Assoc 2016;17(12):1136–1141.
Next Steps
A positive screen triggers confirmatory assessment; a negative screen is reassessed periodically.
- Positive screen → confirm the diagnosis (EWGSOP2 / AWGS): measure muscle strength (handgrip dynamometry or 5-time chair-stand), muscle mass / quantity (BIA or DXA appendicular skeletal muscle mass; calf circumference as a proxy), and physical performance (gait speed, Short Physical Performance Battery, or Timed Up-and-Go) to grade severity.
- Optimize protein-energy intake within CKD-appropriate targets: per KDOQI 2020, roughly 0.55–0.60 g/kg/day for non-dialysis CKD (or 0.28–0.43 g/kg/day with keto-analogues), and 1.0–1.2 g/kg/day for maintenance dialysis, with adequate energy (~25–35 kcal/kg/day). Involve a renal dietitian; consider intradialytic or oral nutrition supplements where indicated.
- Prescribe progressive resistance exercise (with aerobic activity as tolerated), including intradialytic exercise programs where available.
- Treat reversible contributors: correct metabolic acidosis, ensure adequate dialysis dose, address inflammation, vitamin D deficiency, hypogonadism, depression, and polypharmacy; review for protein-energy wasting.
- Negative screen: reassess at routine intervals or sooner if weakness, falls, slowing, or unintentional weight loss develop — and discuss prevention with the patient.
Evidence & References
SARC-F scoring (each item 0–2)
| Item | 0 | 1 | 2 |
|---|---|---|---|
| Strength — lift/carry ~10 lb (4.5 kg) | None | Some | A lot, or unable |
| Assistance walking across a room | None | Some | A lot, use aids, or unable |
| Rising from a chair | None | Some | A lot, or unable without help |
| Climbing a flight of 10 stairs | None | Some | A lot, or unable |
| Falls in the past year | None | 1–3 falls | 4+ falls |
Cut-offs & SARC-CalF
| Quantity | Rule |
|---|---|
| SARC-F total | Sum of five items, 0–10. Positive ≥ 4 |
| Calf-circumference cut-off (low muscle) | Men < 34 cm · Women < 33 cm |
| SARC-CalF total | SARC-F + 10 if calf circumference below cut-off; 0–20. Positive ≥ 11 |
| Unit conversion | Calf (cm) = inches × 2.54 |
SARC-F and SARC-CalF are screening tools with high specificity but modest sensitivity; SARC-CalF improves sensitivity over SARC-F alone. A positive screen warrants confirmatory assessment of muscle strength, mass, and physical performance (EWGSOP2 / AWGS). Calf-circumference thresholds vary by population; 34/33 cm are commonly used and align with Asian (AWGS) values.
Evidence & References
SARC-F is a validated five-item questionnaire designed to rapidly identify patients at risk of sarcopenia and adverse outcomes; SARC-CalF enhances it by incorporating calf circumference, improving sensitivity. Both EWGSOP2 (Europe) and AWGS (Asia) endorse SARC-F or SARC-CalF as the case-finding step before confirmatory testing. In CKD and dialysis, KDOQI 2020 nutrition guidance frames the protein-energy targets used to address muscle loss and protein-energy wasting.
- Malmstrom TK, Morley JE. SARC-F: a simple questionnaire to rapidly diagnose sarcopenia. J Am Med Dir Assoc. 2013;14(8):531–532.
- Barbosa-Silva TG, Menezes AMB, Bielemann RM, et al. Enhancing SARC-F: improving sarcopenia screening in the clinical practice (SARC-CalF). J Am Med Dir Assoc. 2016;17(12):1136–1141.
- Cruz-Jentoft AJ, Bahat G, Bauer J, et al. Sarcopenia: revised European consensus on definition and diagnosis (EWGSOP2). Age Ageing. 2019;48(1):16–31.
- Ikizler TA, Burrowes JD, Byham-Gray LD, et al. KDOQI Clinical Practice Guideline for Nutrition in CKD: 2020 Update. Am J Kidney Dis. 2020;76(3 Suppl 1):S1–S107.
