🧪 Creatinine Clearance Calculator
Cockcroft-Gault Formula with Ideal Body Weight (IBW) Adjustment
| CrCl (mL/min) | CKD Stage | Kidney Function | Clinical Action |
|---|---|---|---|
| >90 | Stage 1 (if damage present) | Normal or High | Monitor annually |
| 60 – 89 | Stage 2 | Mildly Reduced | Lifestyle & monitor |
| 45 – 59 | Stage 3a | Moderately Reduced | Nephrology referral |
| 30 – 44 | Stage 3b | Moderately–Severely Reduced | Medication review |
| 15 – 29 | Stage 4 | Severely Reduced | Prepare for RRT |
| <15 | Stage 5 (ESRD) | Kidney Failure | Dialysis / Transplant |
| Height (cm) | Height (ft) | IBW Male (kg) | IBW Female (kg) |
|---|---|---|---|
| 152 | 5'0" | 50.0 | 45.5 |
| 158 | 5'2" | 55.6 | 51.1 |
| 163 | 5'4" | 61.2 | 56.7 |
| 168 | 5'6" | 66.8 | 62.3 |
| 173 | 5'8" | 72.4 | 67.9 |
| 178 | 5'10" | 77.9 | 73.4 |
| 183 | 6'0" | 83.5 | 79.0 |
| 188 | 6'2" | 89.1 | 84.6 |
| Drug Class | Normal Dose | CrCl <50 mL/min | CrCl <30 mL/min |
|---|---|---|---|
| Metformin | Standard | Reduce dose | Contraindicated |
| Antibiotics (e.g. vancomycin) | Standard | Adjust interval | Extended interval |
| ACE Inhibitors | Standard | Monitor K+ | Use caution |
| NSAIDs | Standard | Avoid if possible | Contraindicated |
| Digoxin | Standard | Reduce dose | Reduce significantly |
| LMWH (e.g. enoxaparin) | Standard | Reduce dose | Use UFH instead |
Creatinine Clearance shows the amount of blood plasma that the kidneys remove of creatinine in one time unit. That testing helps quickly and at low cost estimate, do the kidneys work well. One compares the level of creatinine in the urine with that in the blood.
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Creatinine itself is a useless product. It comes from the creatine in muscles, one filters it through the kidneys, and almost everything one removes as it crosses them.
Creatinine Clearance and Kidney Health
If the kidney activity drops, the creatinine level in blood grows, because less exits by means of urine. One measures the clearance usually in milliliters each minute. Between Creatinine Clearance and GFR, or glomerular screening rate, exists strong link.
Even so they do not match exactly, because a bit of creatinine gets taken back in the nephron. Actually the clearance beats a bit the real GFR, because of the uptake in the proximal tubule beyond the screening in the glomerulus.
The standard range for Creatinine Clearance ranges from 97 to 137 mL/min at men, and from 88 to 128 mL/min at women. Values between 30 and 59 mL/min point to mild decrease of kidney activity. The doctor always must check the results according to the personal health and age.
To estimate Creatinine Clearance most commonly one uses the Cockcroft-Gault formula. It estimates the clearance form the serum creatinine. In 1973 one created it based on data of 249 men.
It requires age, Body Weight, serum creatinine and sex. One does not adjust it to body surface area. The formula commonly overestimates the real clearance, so one must use it carefully.
It can also underestimate the value in persons with a lot of muscle mass.
One can count Creatinine Clearance directly from serum and urinary creatinine together with the urinary amount. The method of 24-hour urine collection seems a bit old approach. Collecting urine during a whole day is hard to do exactly, which causes such results to sometimes bee unreliable.
The muscle mass seriously affects the creatinine level. Persons with bigger muscle naturally make more creatinine as a metabolic by-product. Exercise, especially heavy work, destroys muscle fibers, which raises the level.
Physical activity causes brief increase of serum creatinine because of expanded release from muscle cells, and that clearly does not relate to GFR changes. Muscle mass shrinks with years, and serum creatinine tends to sink more at older men because of this sex related muscle decline. If some own less or more musclethan average, eGFR ratings from creatinine can err.
