If a patient has a creatinine clearance of 90 ml/min, a urine flow rate of 1 ml/min, a plasma K+ concentration of 4 mEq/L, and a urine K+ concentration of 60 mEq/L, what is the approximate rate of K+ excretion?
**Core Concept**
The rate of potassium (K+) excretion is an essential aspect of renal physiology, crucial in maintaining electrolyte balance. It is influenced by factors such as glomerular filtration rate (GFR), tubular reabsorption, and tubular secretion. The kidneys play a vital role in regulating potassium levels through various mechanisms, including the renal potassium handling.
**Why the Correct Answer is Right**
The rate of potassium excretion can be calculated using the formula: K+ excretion (in mEq/min) = urine flow rate (in ml/min) x urine K+ concentration (in mEq/L). Given that the urine flow rate is 1 ml/min and the urine K+ concentration is 60 mEq/L, the rate of K+ excretion can be determined as follows: K+ excretion = 1 ml/min x 60 mEq/L = 60 mEq/min.
**Why Each Wrong Option is Incorrect**
**Option A:** This option would require a different calculation method, such as using the creatinine clearance or plasma K+ concentration, which is not relevant to the given information.
**Option B:** This option might be a distractor, but the actual calculation is straightforward and does not involve complex formulas or additional information.
**Option C:** This option might be attempting to use the plasma K+ concentration or creatinine clearance in the calculation, which is not applicable in this scenario.
**Clinical Pearl / High-Yield Fact**
It's essential to remember that the kidneys play a crucial role in potassium excretion, and factors such as renal function, tubular reabsorption, and secretion influence potassium levels. The kidneys can excrete up to 200-250 mEq of potassium per day, highlighting their importance in maintaining electrolyte balance.
**Correct Answer:** B. 60 mEq/min