**Question:** Anticoagulant used to estimate glucose from a sample sent from PHC is

A. EDTA (Ethylenediamine Tetra Acetic Acid)
B. Sodium Fluoride
C. Lithium Heparin
D. Sodium Chloride

**Correct Answer:** C. Lithium Heparin

**Core Concept:** Anticoagulants are substances added to blood samples to prevent clotting during blood analysis. In primary healthcare centers (PHC), glucose estimation is commonly done using colorimetric assays, where samples are processed and analyzed within a short time frame to maintain accuracy and reliability of the test results.

**Why the Correct Answer is Right:** Lithium Heparin is chosen as the anticoagulant for glucose estimation in PHC because it has a stable pH and does not interfere with the glucose assay. Lithium ions from lithium heparin inhibit platelet aggregation and prevent clotting, ensuring that the blood sample remains clear and free from clots throughout the analysis process.

**Why Each Wrong Option is Incorrect:**

A. EDTA (Ethylenediamine Tetra Acetic Acid): EDTA is a strong chelating agent that forms stable complexes with calcium ions, preventing the activation of coagulation pathways and platelet aggregation. While EDTA is used in some laboratory settings, it may not be suitable for glucose estimation in PHC due to potential interference with the assay results, especially in patients with renal failure or those receiving medications that affect calcium homeostasis.

B. Sodium Fluoride: Sodium Fluoride is primarily used for measuring blood glucose in patients receiving oral glucose tolerance tests (OGTT). It is not suitable for glucose estimation in PHC patients, as it can be influenced by high fluoride levels, which may lead to falsely low blood glucose values.

D. Sodium Chloride: Sodium Chloride is a salt used for preserving the pH balance in blood samples. While it does not interfere with glucose estimation, it is not specifically designed for this purpose and may not provide accurate results compared to Lithium Heparin, making Lithium Heparin the preferred choice for glucose estimation in PHC.

**Clinical Pearl:** In primary healthcare centers, it is essential to use the appropriate anticoagulant to ensure accurate blood glucose estimation in patients. Lithium Heparin is the most suitable anticoagulant for this purpose, while EDTA is not recommended due to potential assay interference. Sodium Fluoride and Sodium Chloride are not specifically designed for glucose estimation and may lead to inaccurate results compared to Lithium Heparin.