§ 493.937 - Toxicology.  


Latest version.
  • § 493.937 Toxicology.

    (a) Program content and frequency of challenge. To be approved for proficiency testing for toxicology, the annual program must provide a minimum of five samples per testing event. There must be at least three testing events at approximately equal intervals per year. The annual program must provide samples that cover the clinically relevant full range of values that would be expected could occur in patient specimens of patients on drug therapy and that cover the level of clinical significance for the particular drug. The samples may be provided through mailed shipments or, at HHS' option, may be provided to HHS or its designee for on-site testing.

    (b) Challenges per testing event. The minimum number of challenges per testing event a program must provide for each analyte or test procedure is five serum, plasma, or blood samples.

    Analyte

    Table 1 to Paragraph (b)—Analyte or Test Procedure

    Acetaminophen, serum.
    Alcohol (blood).
    Blood lead.
    Carbamazepine
  • Digoxin
  • Ethosuximide
  • Gentamicin
  • Lithium
  • Phenobarbital
  • Phenytoin
  • Primidone
  • Procainamide
  • (and metabolite)
  • Quinidine
  • Theophylline
  • Tobramycin
  • Valproic Acid
  • , total.
    Digoxin, total.
    Gentamicin.
    Lithium.
    Phenobarbital.
    Phenytoin, total.
    Salicylate.
    Theophylline.
    Tobramycin.
    Valproic Acid, total.
    Vancomycin.

(c) Evaluation of a laboratory's analyte or test performance. HHS approves only those programs that assess the accuracy of a laboratory's responses in accordance with paragraphs (c)(1) through (4) of this section.

(1) To determine the accuracy of a laboratory's responses for quantitative toxicology tests or analytes, the program must compare the laboratory's response for each analyte with the response that reflects agreement of either 80 percent or more of ten 10 or more referee laboratories or 80 percent or more of all participating laboratories. The score for a sample in toxicology is the score determined under paragraph (c)(2) of this sectionBoth methods must be attempted before the program can choose to not grade a PT sample.

(2) For quantitative toxicology tests or analytes, the program must determine the correct response for each analyte by the distance of the response from the target value. After the target value has been established for each response, the appropriateness of the response must be determined by using fixed criteria based on the percentage difference from the target value

Criteria

.

Table 2 to Paragraph (c)(2)—Criteria for Acceptable Performance

The criteria for acceptable performance
are:
are—
Analyte or test
Criteria for acceptable performance
AcetaminophenTarget value ±15% or ±3 mcg/mL (greater).
Alcohol, bloodTarget Value ±25%±20%.
Blood leadTarget Value ±10% or 4 ±2 mcg/dL (greater).
Carbamazepine, totalTarget Value ±25%. DigoxinTarget Value ±20% or ±0±20% or ±1.0 mcg/mL (greater).
Digoxin, totalTarget Value ±15% or ± 0.2 ng/mL (greater).
EthosuximideTarget Value ±20%.
GentamicinTarget Value ±25%.
LithiumTarget Value ±15% or ±0.3 mmol/L or ±20% (greater).
PhenobarbitalTarget Value ±20%
PhenytoinTarget Value ±25%.
PrimidoneTarget Value ±25%.
Procainamide (and metabolite)Target Value ±25%.
QuinidineTarget Value ±25%±15% or ±2 mcg/mL (greater).
Phenytoin totalTarget Value ±15% or ± 2 mcg/mL (greater).
SalicylateTarget Value ±15% or ±2 mcg/mL (greater).
TheophyllineTarget Value ±20%.
TobramycinTarget Value ±25%. Theophylline±20%.
Valproic Acid, totalTarget Value ±25%±20%. Valproic Acid
VancomycinTarget Value ±25%±15% or ±2 mcg/mL (greater).

(3) To determine the analyte testing event score, the number of acceptable analyte responses must be averaged using the following formula:

(4) To determine the overall testing event score, the number of correct responses for all analytes must be averaged using the following formula:

[57 FR 7151, Feb. 28, 1992, as amended at 58 FR 5229, Jan. 19, 1993; 68 FR 3702, Jan. 24, 2003; 87 FR 41240, July 11, 2022]