Fluid Biochemical Analysis

Function

Fluid Biochemical Analysis involves the chemical examination of fluids accumulated in body cavities (pleural, peritoneal, or pericardial). By measuring levels of protein, lactate dehydrogenase (LDH), glucose, and pH, doctors can apply criteria (like Light's Criteria) to determine the mechanism of fluid accumulation.

Why it is Ordered

This test is ordered when a patient has an effusion (abnormal fluid buildup). The primary goal is to differentiate between a Transudate (fluid leaking due to pressure imbalances) and an Exudate (fluid leaking due to inflammation or injury).

Associated Conditions

• Transudates: Commonly caused by Congestive Heart Failure (CHF), Cirrhosis (Ascites), or Nephrotic Syndrome.
• Exudates: Commonly caused by Bacterial Pneumonia (Parapneumonic effusion), Malignancy (Cancer metastasis), Pulmonary Embolism, or Tuberculosis.
• Chylothorax: Identified by high triglyceride levels in the fluid.

Analysis of glucose levels can also point toward specific causes; for instance, very low glucose in pleural fluid is often associated with Rheumatoid Arthritis or complicated infections.

Summary

This analysis is the first step in diagnosing the root cause of organ dysfunction or systemic disease manifesting as fluid collection, guiding whether the patient needs diuretics (for transudates) or antibiotics/drainage (for exudates).