eGFR 45: What It Means (CKD Stage G3a)
An eGFR of 45 mL/min/1.73m² is KDIGO category G3a (45 to 59). This page explains what it means, the creatinine behind it, and what to ask next.
Medically reviewed by Dr. Rishi Kumar Kafle, MBBS, MD, FASN. Last reviewed October 2026.
An eGFR of 45 mL/min/1.73m² falls in KDIGO category G3a (45 to 59), which means mildly to moderately decreased filtration. At age 50 it matches a creatinine of about 1.81 mg/dL in a man and 1.42 mg/dL in a woman. Below 60 for more than three months meets the KDIGO definition of chronic kidney disease even without albuminuria, so a repeat test is needed to confirm it.
Where 45 Sits Within G3a
An eGFR of 45 sits exactly on the lower edge of G3a: a result of 44 would be G3b. It is 15 points below the G2 line at 60. The KDIGO categories run from G1 to G5; G3a is explained in more depth on the CKD stage 3 page.
G3a is mildly to moderately decreased filtration. If it lasts more than three months it meets the definition of chronic kidney disease on its own, even without albuminuria. Most people have no symptoms at this level; care usually centres on blood pressure, blood glucose, a urine albumin test and a review of medicines.
What Creatinine Gives an eGFR of 45?
The creatinine behind an eGFR of 45 comes from solving the race-free CKD-EPI 2021 equation backwards, by age and sex:
| Age | Man | Woman |
|---|---|---|
| 30 | 2.01 mg/dL (177 µmol/L) | 1.58 mg/dL (139 µmol/L) |
| 40 | 1.91 mg/dL (168 µmol/L) | 1.50 mg/dL (132 µmol/L) |
| 50 | 1.81 mg/dL (160 µmol/L) | 1.42 mg/dL (126 µmol/L) |
| 60 | 1.72 mg/dL (152 µmol/L) | 1.35 mg/dL (119 µmol/L) |
| 70 | 1.63 mg/dL (144 µmol/L) | 1.28 mg/dL (113 µmol/L) |
| 85 | 1.51 mg/dL (133 µmol/L) | 1.19 mg/dL (105 µmol/L) |
A 30-year-old man reaches 45 at 2.01 mg/dL, while an 85-year-old woman reaches it at 1.19 mg/dL. The older the person, the lower the creatinine behind the same eGFR. Nearby creatinine guides: creatinine 1.2 mg/dL (106 µmol/L), creatinine 1.5 mg/dL (133 µmol/L), creatinine 1.8 mg/dL (159 µmol/L), creatinine 1.9 mg/dL (168 µmol/L), creatinine 2.0 mg/dL (177 µmol/L).
eGFR 45 in Absolute mL/min
eGFR is indexed to a body surface area (BSA) of 1.73m². To compare it with a creatinine clearance, or for a very small or large adult, it can be de-indexed with eGFR × BSA ÷ 1.73. For an eGFR of 45, the absolute values are:
| Example adult | BSA (m²) | Absolute GFR (mL/min) |
|---|---|---|
| Man, 40, 178 cm, 80 kg | 1.99 | 52 |
| Woman, 65, 163 cm, 62 kg | 1.67 | 44 |
| Woman, 82, 157 cm, 48 kg | 1.45 | 38 |
| Man, 55, 175 cm, 118 kg | 2.40 | 62 |
What Changes at an eGFR of 45
45 is 15 points above 30, and a fall of about 36% would cross that line. Below 30, KDIGO advises sharing care with a kidney specialist (nephrologist). It is already below 60.
3 of the 9 medicines in our registry whose labels use eGFR have a rule in force at 45. Compared with an eGFR of 50, 2 rules start by 45: metformin (not to be started; the registry advises halving an existing dose); saxagliptin (dose lowered to 2.5 mg).
| Medicine | At eGFR 45 | Next change if eGFR falls |
|---|---|---|
| Metformin | not to be started; the registry advises halving an existing dose | at 29 or lower: contraindicated |
| Sitagliptin | no eGFR rule in force | at 44 or lower: dose lowered to 50 mg |
| Saxagliptin | dose lowered to 2.5 mg | none lower in the registry |
| Dapagliflozin | no eGFR rule in force | at 44 or lower: glucose-lowering effect limited |
| Empagliflozin | no eGFR rule in force | at 29 or lower: glucose-lowering effect limited; other uses follow the indication |
| Canagliflozin | no eGFR rule in force | at 29 or lower: use limited; depends on the indication |
| Spironolactone | no eGFR rule in force | at 29 or lower: avoid |
| Hydrochlorothiazide | no eGFR rule in force | at 29 or lower: ineffective; the registry suggests a loop diuretic instead |
| Glyburide | avoid (CKD stage 3 to 5) | none lower in the registry |
These rows restate our renal dosing registry, which summarises the drug labels. Check the current label and the indication; the prescriber makes the dose decision.
Drug Dosing Cutoffs at eGFR 45
4 drugs in our renal dosing registry have a label cutoff at 45.
Labels That Use eGFR
- Dapagliflozin: eGFR below 45
- Metformin: eGFR 30 to 45
- Saxagliptin: eGFR 45 or below
- Sitagliptin: eGFR below 45
The nearest other cutoffs are up at 50 (16 drugs, listed under eGFR 50) and down at 40 (Piperacillin-Tazobactam, Sotalol). Always confirm the current label, and leave the dose decision to the prescriber.
How a Result of 45 Is Confirmed
A result of 45 is confirmed by repeat testing over time, because one eGFR is a snapshot that can dip with dehydration or illness. Chronic kidney disease is diagnosed only when a low result, or kidney damage, lasts more than three months. Repeat testing, a urine albumin-to-creatinine ratio and, where muscle mass misleads, cystatin C confirm it.
When to Talk to Your Clinician
Bring an eGFR of 45 to your next appointment rather than waiting for symptoms. A repeat test in about three months, a urine albumin check and a medication review are the usual next steps. Seek timely advice for swelling, a marked drop in urine output or new breathlessness, and have kidney function rechecked before and after any scan that uses contrast dye.
Nearby eGFR Results
Or browse all eGFR results. For drug dosing, your clinician may use a creatinine clearance rather than eGFR (see CrCl vs eGFR).