The thick smear is used for screening (higher sensitivity), while the thin smear allows for the identification of the specific Plasmodium species and the calculation of parasite density (parasitemia).

The Schilling test was used to determine if a patient was absorbing B12 properly and to distinguish between different causes of malabsorption, such as a lack of intrinsic factor (Pernicious Anemia).

Ultrasound is the preferred screening method for AAA, especially in men aged 65–75 who have ever smoked, as it is non-invasive and highly accurate at measuring aortic diameter.

The International Normalized Ratio (INR), derived from PT, is the standard for monitoring Warfarin (Coumadin). aPTT is primarily used to monitor unfractionated heparin therapy.

Cystic Fibrosis affects the salt-regulating protein in cells. The sweat chloride test measures the amount of chloride in sweat; high levels are diagnostic for the condition in symptomatic individuals.

The tTG-IgA antibody test is the most sensitive and specific blood test for Celiac Disease. If positive, it is usually followed by an endoscopic biopsy of the small intestine to confirm the diagnosis.

Polysomnography is a comprehensive test that records brain waves, oxygen levels, heart rate, and breathing during sleep, allowing for the calculation of the Apnea-Hypopnea Index (AHI).

Ultrasound is the highly sensitive and specific first-line test for Cholelithiasis (gallstones). It is non-invasive, does not use radiation, and can easily identify stones within the gallbladder.

HbA1c measures the percentage of hemoglobin that has glucose attached to it. Because red blood cells live for about 120 days, this test provides an average of glycemic control over the preceding 8–12 weeks.

Tinel's sign (percussion over the median nerve) and Phalen's maneuver (forced flexion of the wrist) are provocative tests used to elicit tingling or numbness in patients with suspected Carpal Tunnel Syndrome.