🧬 High Creatinine (What it Means)
Gentle explanations for seniors: what creatinine is, why it rises, how it links to eGFR, medicines that affect it, when to repeat labs, and practical next steps.
1 First things first: What is creatinine? â–ľ
Creatinine is a waste product from muscles. Healthy kidneys filter it into urine. A higher blood creatinine generally means the kidneys are filtering less well. But numbers can rise for temporary reasons too—like dehydration, a recent illness, or certain medicines.
- Check the trend, not a single test. Your clinician may repeat labs after hydration or when you’re well.
- eGFR uses creatinine plus age and sex to estimate kidney filtering; muscle mass and some drugs can change creatinine without true kidney damage.
2 Typical lab ranges (and unit converter) â–ľ
Every lab sets its own “reference range.” The examples below are common for adults; your report may differ slightly.
| Group | mg/dL (common) | µmol/L (SI units) | Notes |
|---|---|---|---|
| Adult women | ~0.6–1.1 | ~53–97 | Lower muscle mass → lower creatinine |
| Adult men | ~0.7–1.3 | ~62–115 | Higher muscle mass → higher creatinine |
| Older adults | Varies | Varies | Low muscle can “hide” kidney problems |
Ranges are examples only. Always interpret with eGFR and urine albumin.
Quick converter (mg/dL ↔ µmol/L)
3 Why creatinine goes up (common reasons) â–ľ
Temporary / reversible
- Dehydration (vomiting, diarrhea, hot weather, fasting)
- Recent illness or infection
- Short-term effect from starting certain medicines (see next section)
Kidney stress or injury
- Acute kidney injury (AKI): a sudden rise from illness, low blood flow, toxins
- Chronic kidney disease (CKD): gradual rise over months to years
- Urine blockage (prostate enlargement, stones)
Lab context
- Very low muscle mass can make creatinine look “normal” even if kidneys are weaker
- High muscle or supplements (e.g., creatine) can raise creatinine
4 Medicines that can raise creatinine â–ľ
Never stop a medicine on your own. Some helpful drugs temporarily raise creatinine a little when started; others can harm kidneys if misused.
May cause a small bump (often monitored)
- ACE inhibitors or ARBs (used to protect kidneys/heart)
- SGLT2 inhibitors (diabetes/heart-kidney protection)
- Cimetidine, trimethoprim (can raise measured creatinine without true damage)
- NSAIDs pain pills (e.g., ibuprofen, naproxen) — can reduce kidney blood flow
- Some contrast dyes for scans (need kidney-safe planning)
- High-dose diuretics or dehydration while on diuretics
- Unknown herbal products/supplements
Your prescriber will decide whether a change is expected and safe or a warning sign.
5 How creatinine relates to eGFR & urine albumin â–ľ
- eGFR estimates filtering using creatinine, age, and sex (race-free). Lower eGFR means less filtering.
- Urine albumin (ACR) shows protein leak. Even with “okay” eGFR, protein in urine can raise kidney/heart risk.
- Risk is a combination of eGFR, albumin, blood pressure, diabetes control, and symptoms.
6 What to do when your creatinine is high â–ľ
Right away
- Review the lab report units (mg/dL vs µmol/L) and compare with your last results
- Think about the week before the test: illness, diarrhea, vomiting, heavy exercise, fasting
- List all medicines & OTC pain pills you took
Discuss with your clinician
- Whether to repeat labs after hydration or when recovered
- Check eGFR and urine ACR together
- Whether any medicines should be paused/adjusted
If you have heart failure or advanced CKD, ask for a personal fluid/salt plan.
7 Red flags — seek urgent care ▾
Call emergency services or seek urgent care for any of the following:
- Very little or no urine, severe vomiting, confusion, chest pain, or trouble breathing
- New severe swelling, especially with breathlessness
- Creatinine rising quickly with illness or after a dehydration event
8 Prepare for your appointment â–ľ
- Bring a current medication list (include OTC pain pills and supplements)
- Have your recent labs (creatinine, eGFR, ACR) and note any illnesses or dehydration
- Ask: “Should we repeat labs? Which medicines should I adjust? What’s my target BP and fluid/salt plan?”
9 FAQs â–ľ
Does high creatinine always mean kidney damage?
Not always. Dehydration, temporary illness, and some medicines can raise creatinine without permanent damage. Trends and eGFR/ACR help tell the story.
How fast should I recheck a high creatinine?
It depends on how high it is, your symptoms, and the cause. Many clinicians repeat within days to weeks, sooner if you’re unwell.
Can protein shakes or creatine supplements affect results?
They can. Supplements and high muscle activity may raise creatinine levels. Always share supplement use with your clinician.