Laboratory Tests: General Remarks

How to Cite This Chapter: Don-Wauchope A, Chetty VT, Ivica J, Kavsak P, Khan WI, Lafreniere M, Nouri K, Solnica B. Laboratory Tests: General Remarks. McMaster Textbook of Internal Medicine. Kraków: Medycyna Praktyczna. Accessed May 26, 2024.
Last Updated:
Last Reviewed: May 9, 2022
Chapter Information

1. Order laboratory tests only if their results will inform diagnosis and influence further management.

2. For interpretation of test results, use appropriate reference ranges and decision thresholds provided by the laboratory performing the testing. Reference ranges are flagged in the text with symbols listed below.

3. Ask the laboratory personnel for help if you do not know how to prepare the patient for testing, how to collect and store samples, or if test results do not correspond with the patient’s clinical condition.


Material: AB, arterial blood; CB, capillary blood; P, plasma; S, serum; SA, saliva; U, urine; U24h, urine, 24-hour collection; VB, venous blood.

Reference ranges: !!!, caution: significant differences between methods, instruments, sample types; CPG, clinical practice guideline–recommended reference interval or cut point; CW, choose the recommendation wisely; HRI, harmonized reference interval; LD, laboratory-derived reference range.

Other: ↑, increase; ↓, decrease.

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