INTRODUCTION
"Fixed" grading limits use either a constant concentration (type C limits) or a constant percentage of the target value (type P limits) to define a range of acceptable performance above and below the target value. The target value for qualitative or semi-quantitative results is the most frequently reported (consensus) value(s) of all valid results. The target value for quantitative results is the mean of all results after removal of outliers. In contrast to fixed limits, limits based on standard deviations (SDs) can lead to different grading ranges for the same analyte, even when different peer groups have the same means.
The limits required by CMS consist of all three types
discussed above - fixed concentration (type C), fixed percentage (type P)
and 3SD (type S):
All three types of CMS grading limits are used.
Not all analytes listed have CMS limits. Proficiency testing is not required by HCFA for analytes/procedures which have no CMS-mandated grading limits (although state authorities and accrediting agencies may require them). Such analytes/procedures are identified with a pound sign (#) in the table below as well as on the reporting forms. Results for these CMS-unscored analytes are not included in computing participants' overall CMS subspecialty scores. Therefore these scores do not appear on CMS Cumulative Summary reports; they appear only on graded reports (which do not go to CMS).
In the interest of uniformity, the limits used for CMS-unscored analytes are derived from those used for CMS-scored analytes which are similar.
# : Indicates analytes for which proficiency testing is not required by CMS and whose scores are not included in computing CMS subspecialty scores.
| PROGRAM/ANALYTE | CONCENTRATION | PERCENT |
| Alcohol, Serum | none | 25 |
| # Ammonia, Serum | 10 umol/L | 5 |
| pH | 0.04 | none |
| pCO2 | 5.0 mm Hg | 8 |
| pO2 | 3SD | |
| # Ionized Calcium | 0.25 mmol/L | none |
| Cl, K and Na | see Basic Chemistry | |
| # Blood Lead | 4.0 ug/dL | 10 |
| # BNP | 3SD | |
| Basic Chemistry | ||
| Albumin | none | 10 |
| # Bicarbonate (Total CO2) | 4 mEq/L | 20 |
| Bilirubin, Total | 0.4 mg/dL | 20 |
| Calcium | 1.0 mg/dL | none |
| Chloride | none | 5 |
| Cholesterol, Total | none | 10 |
| Creatinine | 0.3 mg/dL | 15 |
| Glucose | 6 mg/dL | 10 |
| # Phosphorus | 0.4 mg/dL | 15 |
| Potassium | 0.5 mEq/L | none |
| Pregnancy, Serum | pos/neg | |
| Sodium | 4 mEq/L | none |
| Total Protein | none | 10 |
| Triglycerides | none | 25 |
| Urea Nitrogen | 2 mg/dL | 9 |
| Uric Acid | none | 17 |
| i-STAT Chemistry | ||
| # Bicarbonate (Total CO2) | 4 mEq/L | 20 |
| # Calcium, Ionized | 0.25 mmol/L | none |
| Chloride | none | 5 |
| Creatinine | 0.3 mg/dL | 15 |
| Glucose | 6 mg/dL | 10 |
| Hematocrit | none | 6 |
| Hemoglobin | none | 7 |
| # Lactate | none | 25 |
| Potassium | 0.5 mEq/L | none |
| Sodium | 4 mEq/L | none |
| Urea Nitrogen | 2 mg/dL | 9 |
| Comprehensive Chemistry | ||
| Alanine Aminotransferase | none | 20 |
| Alkaline Phosphatase | none | 30 |
| Amylase | none | 30 |
| Aspartate Aminotransferase | none | 20 |
| Creatine Kinase | none | 30 |
| Cortisol | none | 25 |
| # gamma-Glutamyl-transferase | 10 IU/L | 20 |
| Human Chorionic Gonadotropin | 3SD | |
| Iron | none | 20 |
| # Lipase | none | 30 |
| Lactate Dehydrogenase | none | 20 |
| Magnesium | none | 25 |
| Thyroid Stimulating Hormone | 3SD | |
| Thyroxine, Free | 3SD | |
| Thyroxine, Total | 1.0 µg/dL | 20 |
| Triiodothyronine, Total (T3) | 3SD | |
| TUptake | 3SD | |
| # Direct Bilirubin | 0.4 mg/dL | 20 |
| Fertility Endocrinology | ||
| # DHEA-S | 6.0 ug/dL | 15 |
| # Estradiol | 3 pg/mL | 30 |
| # Follicle-Stimulating Hormone | 2 mIU/mL | 25 |
| # Luteinizing Hormone | 2 mIU/mL | 25 |
| # Progesterone | 0.3 ng/mL | 30 |
| # Fructosamine | ||
| Polylysine | 45 mmol/L | 30 |
| DMF | 0.45 mmol/L | 30 |
| # Glycohemoglobin | 1.0 % | 25 |
| Cardiac Markers / Isoenzymes | ||
| # BNP | 5.0 pg/mL | 20 |
| CK2 Isoenzyme (CKMB) | 3SD | |
| # LD Isoenzymes 3-5 | 3.0 % | 30 |
| # Myoglobin | 15 ng/mL | 30 |
| # Troponin I | 0.9 ng/mL | 30 |
| # Troponin T | 0.1 ng/mL | 30 |
| Lipids | ||
| # Apolipoprotein A1 | 25 mg/dL | 30 |
| # Apolipoprotein B | 20 mg/dL | 25 |
| HDL Cholesterol | none | 30 |
| # LDL Cholesterol (Direct) | 15 mg/dL | 20 |
| # Lipoprotein (a) | 10 mg/dL | 30 |
| Lipids, Waived | ||
| #Cholesterol, Total | none | 10 |
| #HDL Cholesterol | none | 30 |
| # Triglycerides | none | 25 |
| PTH / Insulin / C-peptide | ||
| # C-peptide | 0.1 ng/mL | 30 |
| # Insulin | 1.5 uIU/mL | 30 |
| # PTH | 0.9 pg/mL | 25 |
| Special Chemistry | ||
| # Ferritin | 4.5 ng/mL | 30 |
| # Folate | 0.9 ng/mL | 30 |
| # Homocysteine | 2.5 umol/L | 20 |
| # Prolactin | 3.6 ng/mL | 30 |
| # Prostate-Specific Antigen | 0.9 ng/mL | 30 |
| # Triiodothyronine, Free (Free T3) | 1.5 pg/mL | 30 |
| # Testosterone | 0.3 ng/mL | 30 |
| # Vitamin B12 | 60 pg/mL | 30 |
| Therapeutic Drug Monitoring | ||
| # Acetaminophen | 2.5 mg/mL | 25 |
| Carbamazepine | none | 25 |
| Digoxin | 0.2 ng/mL | 20 |
| Gentamicin | none | 25 |
| Lithium | 0.3 mEq/L | 20 |
| Phenobarbital | none | 20 |
| Phenytoin | none | 25 |
| Primidone | none | 25 |
| Procainamide | none | 25 |
| Procainamide, N-Acetyl (NAPA) | none | 25 |
| Quinidine | none | 25 |
| # Salicylates | none | 25 |
| Theophylline | none | 25 |
| Tobramycin | none | 25 |
| Valproic Acid | none | 25 |
| # Vancomycin | 1.5 mg/mL | 25 |
| TIBC/UIBC | ||
| # Total Iron Binding Capacity (TIBC) | none | 25 |
| # Unsaturated Iron Binding Capacity (UIBC) | none | 25 |
| Tumor Markers | ||
| # Beta 2 microglobulin | 0.06 mg/L | 30 |
| # CA-125 | 9 U/mL | 30 |
| # Carcinoembryonic Antigen | 1.2 ng/mL | 30 |
| # Prostrate-Specific Antigen, Free | 0.9 ng/mL | 30 |
| Urinalysis | ||
| # Specific Gravity | 0.010 | none |
| # Urine Microalbumin | 10 mg/L | 25 |
| # Urine Creatinine | 3 mg/dL | 15 |
| Urine Chemistry | ||
| # Amylase | none | 30 |
| # Calcium | 1.0 mg/dL | none |
| # Chloride | none | 5 |
| # Creatinine | 3.0 mg/dL | 15 |
| # Glucose | 6 mg/dL | 10 |
| # Osmolality | 9. mOsm/kg | 10 |
| # Phosphorus | 3. mg/dL | 15 |
| # Potassium | 3. mEq/L | 15 |
| # Sodium | 4. mEq/L | 4 |
| # Total Protein | 1.0 mg/dL | 25 |
| # Urea Nitrogen | none | 9 |
| # Uric Acid | none | 17 |
| Whole Blood Glucose | 6 mg/dL | 10 |
| Coagulation | ||
| # Activated Clotting Time | none | 20 |
| Activated Partial Thrombo Time | none | 15 |
| Fibrinogen | none | 20 |
| Prothrombin Time (PT) | none | 15 |
| INR | none | 20 |
| # D-Dimer | none | 30 |
| Whole Blood Prothrombin Time | none | 15 |
| INR | none | 20 |
| CoaguChek Prothrombin Time (all instruments) | none | 15 |
| INR | none | 20 |
| Andrology | ||
| # Sperm Count | 3 million/mL | 25 |
| # Sperm Morphology | 5% normal | 20% |
| # Sperm Motility | 5% | 15% |
| # Sperm Viability | 5% viable | 20% |
| Hematology (all programs) | ||
| Automated Differential | 3SD | |
| Erythrocytes | none | 6 |
| Hematocrit | none | 6 |
| Hemoglobin | none | 7 |
| Leukocytes | none | 15 |
| Platelets | none | 25 |
| Reticulocyte Count | 0.5% | 30 |
| Erythrocyte Sedimentation Rate (ESR) | 3SD | |
| Erythrocyte Sedimentation Rate (ESR) - Rapid | 3SD | |
| Immunoproteins | ||
| Alpha-1-Antitrypsin | 3SD | |
| Complement C3 | 3SD | |
| Complement C4 | 3SD | |
| IgA | 3SD | |
| IgE | 3SD | |
| IgG | none | 25 |
| IgM | 3SD | |
| Diagnostic Immunology | ||
| CRP | 0.4 mg/dL | 3 SD |
| high sensitivity CRP | 0.4 mg/L | 3 SD |
# : Indicates analytes for which proficiency testing is not required by CMS and whose scores are not included in computing CMS subspecialty scores.