TN 2 (07-16)
DI 24555.005 Using Laboratory Testing to Evaluate Genitourinary Impairments
This section provides information about laboratory testing we use to help us evaluate genitourinary disorders under the criteria in listings 6.05, 106.05, and 6.06. We can also use laboratory test results when evaluating genitourinary impairments at steps 4 and 5 of the sequential evaluation process.
For more information about evaluating chronic kidney disease, see DI 34001.020 and DI 34005.106.
B. Glomerular filtration rate (GFR) and estimated glomerular filtration rate (eGFR)
GFR is the rate at which the kidneys filter waste and extra fluid from the blood, measured in milliliters per minute. Although it is possible to measure the GFR directly, the process is intrusive and time-consuming. Therefore, most treating sources use an eGFR as the measure of kidney function. We consider eGFR results under the criteria in listings 6.05 and 106.05.
1. Equations for calculating eGFR
Laboratories may use different equations to calculate eGFR. Equations consider serum creatinine levels and some or all of the following factors: age, gender, body size, and race. Race is not a factor in eGFR equations for children. We consider all eGFR equations when we evaluate chronic kidney disease under listings 6.05 and 106.05.
Examples of eGFR equations include:
The Modification of Diet in Renal Disease (MDRD) equation (used for adults age 18 or older),
The Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation (used for adults age 18 or older), or
The Bedside Schwartz equation (for children under age 18).
NOTE: Do not calculate the eGFR if the laboratory did not provide it, except when adjusting for race in DI 24555.005B.3. (in this section).
2. Laboratory reporting of eGFR
Current medical practice guidelines recommend reporting different eGFR values based on a person’s race. Due to a higher average muscle mass and creatinine production, African American adults have a higher eGFR than adults of other races.
Laboratories may report:
One eGFR value appropriate for the person’s identified race,
An eGFR value for African Americans and another eGFR value for other races, or
One eGFR value for other races and an instruction to multiply this value by an adjustment factor (usually recorded next to the eGFR value in the laboratory report) if the person is African American.
3. Using the appropriate eGFR value
We should use the eGFR value appropriate for a person’s race.
If the person is African American:
Use the African American eGFR value, or
If the laboratory did not provide the African American eGFR value, but provided an adjustment factor, multiply the eGFR value by the adjustment factor, or
If the laboratory did not provide the African American eGFR value or the adjustment factor, or it is unclear whether the laboratory adjusted the eGFR value for race, contact the medical source to determine the appropriate eGFR value.
If the person’s race is unknown and multiplying the eGFR value by the adjustment factor may affect the determination of the claim (eGFR values between 17 ml/min/1.73m2 and 20 ml/min/1.73m2):
Review the evidence in the file to determine the person’s race and multiply the eGFR value by the adjustment factor when applicable, or
If the person’s race cannot be determined from the evidence in the file, use the unadjusted eGFR value in the laboratory report.
NOTE: For adults, eGFR values of 16 ml/min/1.73m2 or lower will meet the requirement in listing 6.05A of 20 ml/min/1.73m2 or less, regardless of race.
C. Urine total-protein-to-creatinine ratio (UPCR)
The UPCR reflects the relationship between the urine total protein to the urine total creatinine. We consider the UPCR under the criteria in listing 6.06.
1. Laboratory reporting of UPCR
If a laboratory provides both the urine total protein and urine total creatinine values, it will usually report them using the same units of measurement. In this instance, the laboratory will normally include the UPCR in the report. We accept UPCR values calculated from random (spot) urine samples or timed collections (including 24-hour collections).
2. Calculating UPCR
If the laboratory does not provide the UPCR, we may calculate the ratio if all of the following apply to the urine total protein and urine total creatinine values:
Reported in the same units of measurement,
Recorded on the same laboratory report, and
Performed on the same day.
To calculate the UPCR, divide the urine total protein by the urine total creatinine.
NOTE: Use laboratory values from urine tests to calculate the UPCR. Laboratories sometimes report serum creatinine values instead of urine creatinine. Do not use serum creatinine laboratory values to calculate the UPCR.
D. Urine albumin-to-creatinine ratio (ACR)
The ACR reflects the relationship between the urine albumin to the urine creatinine. Albumin is one of the proteins measured in the UPCR. We may use the ACR to evaluate medical equivalence under listing 6.06. For purposes of medical equivalence, an ACR value that is equal to or greater than 3.5 is of equal medical significance to a UPCR of 3.5 or greater. We accept ACR values calculated from random (spot) urine samples or timed collections (including 24-hour collections).