Altered Creatinine

Summary

Creatinine above thirty is necessary to produce reliable test results. This can be achieved by limiting fluid intake while collecting urine specimen.

History

This three-year-old autistic child's urinary markers were altered secondary to a low creatinine. In follow-up testing, when the creatinine was above 30 mg/dl, i.e. in normal range, shifts in data occured that were clinically significant.

Age

3

Gender

Male

Description of Results

In order to assure urine specimen adequacy, creatinine is used as a benchmark for urinary analyte concentration. Creatinine must be above 30 mg/dl in order for test results to have meaning and be reflective of "true" ranges. Creatinine in most adults falls around 100 mg/dl and in a child around 75 mg/dl. However, as long as a creatinine of 30 mg/dl is achieved, test results are reliable.

The following data, from a 3-year-old autistic child, is indicative of results that occur when a creatinine falls too low, in this case 10 mg/dl. Notice that most lab values are extremely elevated. For example, citrate is 4000, about 4.5 times higher than the top of normal range. Cis-aconitate and isocitrate are too high to quantify. Anomalolously high results can be produced due to non-linear corrections of dilution when creatinine is very low.

The parents report that during the collection of urine for the Organix Profile the child was consuming copious amounts of fluid, including drinking large glasses of water during the night of urine collection. This results in a diluted creatinine.

It was advised that fluid intake be restricted for retesting. The parents eliminated the nighttime water during the second urine collection. With fluid restriction the creatinine climbed to 34 mg/dl. While many of the lab values remain high, as is typical in autism, the highs fell to more realistic readings.

In cases such as these retesting is optimal, but some extrapolation can be made. If creatinine is less than 30 mg/dl, the values can be divided by two to give more accurate information. If creatinine is less than 20 mg/dl divide patient values by 3. In the case of alpha-ketoisovalerate the original Organix Profile provided a reading of 2.2. When divided by three this gives a value of 0.73. Upon retesting when an appropriate creatinine level was achieved the alpha-ketoisovalerate level is 0.7. Many of the other values fall close to the re-test values as well when divided by a factor of 3.

Recommendations

Restricting fluid intake during urine collection can be an appropriate technique to assure a creatinine level greater than 30 mg/dl to assure adequate test results.

Other Comments

These two sets of data from the same patient illustrate the necessity of a creatinine higher than 30 to assure a valid reading and the importance of coaching a patient to proper urine collection technique.