Short answer: There’s no single required checklist, but a sensible baseline before starting a GLP-1 with kidney disease includes your kidney function (eGFR, ideally with cystatin C), urine protein (UACR), electrolytes, and blood sugar (A1c) — plus a review of your current medicines. These give you and your doctor a starting point to spot changes safely as you lose weight.
Why a baseline matters. GLP-1 drugs change several things that show up on labs — weight (and sometimes muscle), blood sugar, blood pressure, and hydration. Having “before” numbers makes it much easier to tell a real change from normal noise later on.
Tests worth having before you start:
- eGFR (kidney function). Your baseline filtering level. Because rapid weight/muscle loss can distort the usual creatinine estimate, ask whether a cystatin C (or combined creatinine–cystatin C) eGFR would give a cleaner baseline.
- Urine albumin-to-creatinine ratio (UACR). The amount of protein leaking into your urine — one of the best markers of kidney health and of whether treatment is helping over time.
- Basic metabolic panel (electrolytes). Sodium, potassium, bicarbonate, and creatinine — useful before and during treatment, especially if you take diuretics or ACE inhibitors/ARBs.
- A1c and/or glucose. Your blood-sugar baseline. Important if you have diabetes, and for spotting hypoglycemia risk if you also take insulin or a sulfonylurea.
- Weight and, if available, body composition. A baseline weight (and ideally a muscle/fat estimate) helps track whether you’re losing fat rather than muscle.
Also review — not a blood test, but just as important:
- Your medicine list. Flag diuretics, ACE inhibitors/ARBs, NSAIDs, SGLT2 inhibitors, insulin, and sulfonylureas — these interact with the dehydration and blood-sugar effects of GLP-1 drugs and shape your sick-day plan.
- Blood pressure. A baseline reading, since GLP-1 drugs can nudge it down.
How often to recheck. That’s individualized, but many clinicians recheck kidney function and electrolytes periodically as you titrate and lose weight, and sooner if you have an illness with vomiting or diarrhea.
Bottom line. A simple baseline — eGFR (± cystatin C), UACR, electrolytes, A1c, plus a medicine review — sets you up to use a GLP-1 safely with kidney disease and to see clearly whether it’s helping.
Full guide: Semaglutide (Ozempic/Wegovy) and Your Kidneys.
Related questions
Do I need a cystatin C test before starting? It’s not mandatory, but it’s helpful — especially if you expect fast weight loss — because it gives a muscle-independent baseline for your kidney function.
Should I check urine protein before a GLP-1? Yes, a UACR is one of the most useful baselines. A falling UACR over time is a strong sign the kidney is doing better.
How soon should I recheck my kidney labs after starting? Timing is individualized, but expect periodic rechecks as you titrate — and prompt testing if you get sick with vomiting or diarrhea.
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Written and medically reviewed by Dr. Amir S. Naderi, MD, FASN. Last updated: July 8, 2026. Educational information only — not medical advice. Never change or stop a prescribed medication without talking to your doctor.