Dilute Specimen

A drug test specimen with creatinine and specific gravity values below normal range, indicating excessive fluid intake before the test.

Key Facts

  • Creatinine level between 2–20 mg/dL and specific gravity 1.0001–1.0029
  • Can be positive-dilute or negative-dilute
  • Employer may (but is not required to) order a single retest
  • Creatinine below 2 mg/dL is "substituted" — treated as refusal
  • Excessive fluid intake is the most common cause

A dilute specimen occurs when a drug test sample has a creatinine concentration between 2 and 20 mg/dL and a specific gravity between 1.0001 and 1.0029. This typically results from drinking excessive fluids before the test. A dilute result can be either positive-dilute (substance detected despite dilution) or negative-dilute (no substance detected). Under DOT rules, a positive-dilute is treated as a positive result. For negative-dilute results, the employer may direct the employee to take another test immediately, but only one retest is allowed. If creatinine is below 2 mg/dL, the specimen is considered "substituted" and treated as a refusal to test.

Drug Test Results & Specimen Issues Compared

Understanding the different outcomes and specimen-related issues in drug testing.

TypeMeaningReported ByNext StepsMRO Role
PositiveConfirmed presence above cutoffLaboratory → MROMRO interview, then report to employerVerify with donor — medical explanation?
NegativeNo substances detected above cutoffLaboratory → MROEmployee clearedReview and release result
DiluteCreatinine 2–20 mg/dL & SG 1.0001–1.0029Laboratory → MROEmployer may request retest (one time)Report as negative-dilute or positive-dilute
Shy Bladder / Shy LungUnable to provide sufficient specimenCollectorMedical evaluation within 5 daysEvaluate medical explanation

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