Fast Five Quiz: Is Your Knowledge of Chronic Kidney Disease Sufficient?

Vecihi Batuman, MD


April 20, 2018

Testing in patients with CKD typically includes a complete blood count (CBC), basic metabolic panel, and urinalysis, with calculation of renal function. Normochromic normocytic anemia is commonly seen in CKD. Other underlying causes of anemia should be ruled out. The blood urea nitrogen (BUN) and serum creatinine levels will be elevated in patients with CKD. Hyperkalemia or low bicarbonate levels may be present. Serum albumin levels may also be measured, as patients may have hypoalbuminemia as a result of urinary protein loss or malnutrition. A lipid profile should be performed in all patients with CKD because of their risk for cardiovascular disease. Serum phosphate, 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D, alkaline phosphatase, and intact PTH levels are obtained to look for evidence of renal bone disease.

A retrograde pyelogram may be indicated if a high index of clinical suspicion for obstruction is noted despite a negative finding on renal ultrasonography. Intravenous pyelography is not commonly performed because of the potential for renal toxicity from the intravenous contrast; however, this procedure is often used to diagnose renal stones.

According to guidelines from the National Kidney Foundation's Kidney Disease Outcomes Quality Initiative (KDOQI), in adult patients who are not at elevated risk for CKD, screening for proteinuria can be done with a standard urine dipstick. For screening patients at elevated risk, KDOQI recommends using an albumin-specific dipstick; this is because albuminuria is a more sensitive marker than total protein for CKD from diabetes, hypertension, and glomerular diseases.

Although most clinical laboratories routinely include an estimated GFR (eGFR) calculated from the measured serum creatinine level using the MDRD formula, the Cockcroft-Gault formula can also be a convenient tool for estimating creatinine clearance (CrCl). The formulas are as follows:

  • CrCl (male) = ([140-age] × weight in kg)/(serum creatinine × 72)

  • CrCl (female) = CrCl (male) × 0.85

The Cockcroft-Gault formula performs better for estimating the GFR in patients with normal kidney function (GFR at levels above 60 mL/min/1.73 m2) compared with the MDRD formula, which underestimates the measured GFR.

For more on the workup of CKD, read here.


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