OSMT (Ontario Society of Medical Technologists) Practice Exam

What is the specific gravity test for haemoglobin used for?

1. Uses copper nitrate

2. Is a screening test for blood donors

3. Uses the principle that RBC's sink quickly if anemia is suspected

4. All of the above

The correct answer is: Uses the principle that RBC's sink quickly if anemia is suspected

The specific gravity test for hemoglobin is primarily used to assess the density of red blood cells (RBCs) in a sample, which can provide insights into conditions such as anemia. The principle behind this test involves the observation that RBCs will sink quickly if there is a low concentration of hemoglobin, indicative of anemia. This rapid sinking occurs due to a decrease in the number of RBCs or their hemoglobin content, both of which contribute to the overall specific gravity of the blood sample. The other options provided may introduce related concepts but do not accurately describe the focal application of the specific gravity test for hemoglobin. For instance, while some tests for hemoglobin can be used in blood donation settings, the specific gravity test is not routinely classified as a screening test for blood donors. Similarly, while copper nitrate might have relevance in other testing methodologies, it is not utilized in the specific gravity test for hemoglobin. Thus, focusing on the sinking behavior of RBCs is key to understanding the primary function of this particular assessment.