Enter urine potassium and urine creatinine into the Potassium to Creatinine Ratio Calculator. Use the Urine K/Cr tab for the clinically common urine potassium-to-creatinine ratio (reported as mmol/mmol or mEq/g creatinine). The Basic (P/C×100%) tab is a simple percent form when potassium and creatinine are entered in the same mass units (not the usual clinical reporting format for urine K/Cr).
Potassium to Creatinine Ratio Formula
The potassium-to-creatinine ratio is most commonly used as a urine index and is typically reported with units (for example, mmol/mmol or mEq/g creatinine). If you choose to express a same-unit ratio as a percentage, multiply by 100.
\begin{aligned}
\text{K/Cr} &= \frac{K}{Cr}\\
\text{Percent (optional)} &= \frac{K}{Cr}\times 100
\end{aligned}- Where K/Cr is the potassium-to-creatinine ratio (commonly a urine ratio)
- K is potassium (often urine potassium concentration, e.g., mmol/L or mEq/L)
- Cr is creatinine (often urine creatinine concentration, e.g., mmol/L or mg/dL)
To calculate the potassium-to-creatinine ratio, divide potassium by creatinine after ensuring the units are compatible for the form you want to report (e.g., mmol/mmol or mEq/g creatinine).
How to Calculate Potassium to Creatinine Ratio?
The following example problem outlines how to calculate a urine potassium-to-creatinine ratio.
Example Problem #1:
- First, determine the urine potassium concentration.
- The urine potassium is given as: 40 mmol/L.
- Next, determine the urine creatinine concentration.
- The urine creatinine is provided as: 120 mg/dL.
- Finally, calculate the potassium-to-creatinine ratio using the equation above (convert creatinine to compatible units as needed).
K/Cr = K / Cr
The values given above are inserted into the equation below and the solution is calculated:
Cr = 120 mg/dL × 0.0884 = 10.61 mmol/L, so K/Cr = 40 / 10.61 = 3.77 mmol/mmol. (Equivalently: Cr = 120 mg/dL = 1.20 g/L, so K/Cr = 40 / 1.20 = 33.33 mEq/g creatinine.)
FAQ
What is the significance of the Potassium to Creatinine Ratio?
In clinical practice, the urine potassium-to-creatinine ratio (urine K/Cr) is commonly used when evaluating hypokalemia to help assess whether the kidneys are inappropriately wasting potassium. A higher urine K/Cr can suggest renal potassium loss (depending on context), while a lower value is more consistent with appropriate renal conservation. It is not a substitute for measuring blood (serum) potassium.
How often should the Potassium to Creatinine Ratio be tested?
How often it is checked depends on the clinical situation (for example, evaluation of hypokalemia or monitoring certain medications) and your clinician’s guidance.
Can diet affect the Potassium to Creatinine Ratio?
Yes. Higher dietary potassium intake (or supplements) can increase urinary potassium excretion and may increase a urine K/Cr result. In people with kidney disease or those taking certain medications, dietary potassium can also raise blood potassium. Discuss diet changes with a healthcare professional if you have kidney disease or abnormal potassium levels.
