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Estimated glomerular filtration rate (GFR)

Source: R/kidney.R
calculate_GFR.Rd

This function calculates the estimated glomerular filtration rate (GFR) according to Finlay's formula, where serum creatine is in mg/dL. The calculation takes into account the respondent's ethnicity, sex, and age.

Usage

calculate_GFR(LAB_BCRE, PGDCGT, CLC_SEX, CLC_AGE)

Arguments

LAB_BCRE

Blood creatine (µmol/L). It should be a numeric value between 14 and 785.

PGDCGT

Ethnicity (13 categories). It should be an integer value between 1 and 13.

CLC_SEX

Sex (Male = 1, Female = 2). It should be an integer value of either 1 or 2.

CLC_AGE

Age (years). It should be a numeric value between 3 and 79.

Value

The calculated GFR as a numeric value. If any of the input parameters (LAB_BCRE, PGDCGT, CLC_SEX, CLC_AGE) are non-response values (LAB_BCRE >= 996, PGDCGT >= 96, CLC_SEX >= 6, CLC_AGE >= 996) or out of bounds, the GFR will be NA(b).

Details

The function uses the serum creatine level (LAB_BCRE) in µmol/L to calculate the estimated GFR. First, it checks if any of the input parameters are non-response values. If any non-response values are found, the GFR will be set to NA, and the function will return immediately. Otherwise, it proceeds with the calculation by converting the serum creatine to mg/dL (serumcreat = LAB_BCRE / 88.4). Based on the respondent's ethnicity (PGDCGT), sex (CLC_SEX), and age (CLC_AGE), the appropriate formula is applied to calculate the GFR. The formula used for each combination of ethnicity and sex is as follows:

     - Female and Black (PGDCGT == 2, CLC_SEX == 2): GFR = 175 * ((serumcreat)^(-1.154)) * ((CLC_AGE)^(-0.203)) *
                                                    (0.742) * (1.210)
     - Female and not Black (PGDCGT != 2, CLC_SEX == 2): GFR = 175 * ((serumcreat)^(-1.154)) * ((CLC_AGE)^(-0.203)) *
                                                        (0.742)
     - Male and Black (PGDCGT == 2, CLC_SEX == 1): GFR = 175 * ((serumcreat)^(-1.154)) * ((CLC_AGE)^(-0.203)) *
                                                  (1.210)
     - Male and not Black (PGDCGT != 2, CLC_SEX == 1): GFR = 175 * ((serumcreat)^(-1.154)) * ((CLC_AGE)^(-0.203))

Examples


# Example 1: Calculate GFR for a 45-year-old white female with serum creatine of 80 µmol/L.
calculate_GFR(LAB_BCRE = 80, PGDCGT = 1, CLC_SEX = 2, CLC_AGE = 45)
#> [1] 67.27905
# Output: GFR = 67.27905

# Example 2: Calculate GFR for a 35-year-old black female with serum creatine of 70 µmol/L.
calculate_GFR(LAB_BCRE = 70, PGDCGT = 2, CLC_SEX = 2, CLC_AGE = 35)
#> [1] 99.94114
# Output: GFR = 99.94114