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

Vecihi Batuman, MD; Patrick Rossignol, MD


July 21, 2022

Normochromic normocytic anemia is commonly seen in CKD and found during laboratory testing. Other underlying causes of anemia should be ruled out (ferritin, transferrin saturation, or C-reactive protein). The workup for CKD typically includes estimated GFR assessment (using serum creatinine, and ideally the Chronic Kidney Disease Epidemiology Collaboration [CKD-EPI] formula, rather than the Cockcroft-Gault formula, which might be somehow biased, see below) and urinalysis (including albumin/creatinine ratio and counting of red and white blood cells).

A complete blood cell count, basic metabolic panel, and urinalysis with calculation of renal function are also warranted.

Hyperkalemia or low bicarbonate levels may be present. Serum albumin levels should also be measured, as patients may have hypoalbuminemia because of urinary protein loss or malnutrition. A lipid profile (eg, total, high-density lipoprotein/low-density lipoprotein cholesterol/triglycerides) 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 parathyroid hormone levels are obtained to look for evidence of renal bone disease in patients with advanced CKD (< 45 mL/min/1.73 m2).

Retrograde pyelography or MRI 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.

Urinary albumin-to-creatine ratio using an early morning urine sample is the preferred measurement for initial testing of albuminuria. A routine urine dipstick lacks the sensitivity to detect small amounts of urine protein, meaning patients at high risk who could benefit from evidence-based interventions may be missed.

The Cockcroft-Gault formula is 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

However, weight by itself may induce biases, for example, in obese or in cachectic patients, as well as in fluid overloaded patients.

The Modification of Diet in Renal Disease (MDRD) Study equation is an alternative method that can be used to calculate the GFR. This equation does not require a patient's weight. However, the MDRD underestimates the measured GFR at levels > 60 mL/min/1.73 m2. Stevens and colleagues found that the CKD-EPI equation is more accurate than the MDRD study equation overall and across most subgroups and that it can report estimated GFRs that are ≥ 60 mL/min/1.73 m2 .

Learn more about the workup of CKD.


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