This is a highly specialized, diagnostic test used by your medical team in a hospital or clinical setting. It measures the potassium level in a specific sample of body fluid (such as fluid from a wound drain or cyst). The result is then compared to your blood potassium level. This information is critical for helping your doctor identify the source or nature of the fluid, which is vital for an accurate diagnosis and treatment plan. This technical test provides the precise, diagnostic clues your care team needs.