Blood work refers to laboratory tests conducted on a blood sample. Being unwell can influence the results of these tests. Illness introduces various physiological changes within the body, which can alter numerous blood parameters, making it important to understand these potential impacts on test readings.
How Illness Influences Test Results
Illness triggers physiological responses that alter blood test readings. A primary mechanism is inflammation, the body’s immune response to infection or injury. This response leads to systemic changes, including the release of signaling molecules that influence cell production and activity in the bloodstream.
Dehydration, often accompanying illnesses like fever, vomiting, or diarrhea, also affects blood composition. Fluid loss can concentrate blood components, leading to elevated readings for certain markers. The body’s stress response, mediated by hormones such as cortisol, can temporarily alter metabolism and various physiological processes, influencing test results. Additionally, illness can induce metabolic changes, temporarily affecting how the body processes nutrients and eliminates waste products.
Specific Blood Marker Changes
Illness commonly affects specific blood test parameters. A Complete Blood Count (CBC) frequently shows alterations; White Blood Cell (WBC) counts often elevate in bacterial infections. Viral infections might initially cause a drop in WBCs before an increase, or specific changes in the differential count of various white blood cell types. Red Blood Cell (RBC) counts, hemoglobin, and hematocrit can appear elevated due to dehydration or may decrease in cases of chronic illness leading to anemia. Platelet counts, which are involved in clotting, can increase with inflammation or decrease in severe infections.
Metabolic panels also reflect illness-related changes. Electrolytes can fluctuate due to dehydration, vomiting, or diarrhea. Blood glucose levels may rise due to the stress hormones released during illness. Kidney function markers can become elevated, indicating dehydration or a direct impact of severe illness on the kidneys. Liver Function Tests (LFTs), including ALT and AST, might show mild elevations in systemic illness or more significant changes if the liver is directly affected by a specific infection.
Inflammatory markers are sensitive to illness. C-Reactive Protein (CRP) levels typically rise during inflammation and infection. Erythrocyte Sedimentation Rate (ESR) also tends to be elevated in inflammatory conditions, as increased proteins in the blood cause red blood cells to settle more rapidly. These changes in blood markers are often temporary, resolving as the body recovers from the illness.
Interpreting Results When Unwell
When a patient is unwell, providing comprehensive information to the healthcare provider is important for accurate interpretation of blood test results. Patients should always inform their doctor about any symptoms of illness, even seemingly minor ones like a common cold, before or during blood tests. This disclosure offers crucial context for understanding any abnormal readings.
Healthcare providers recognize that illness can skew blood test results and account for a patient’s current symptoms and medical history when evaluating the findings. They might order follow-up tests once the patient has recovered to establish baseline values, or they may interpret initial results differently in the context of an acute illness. Doctors use their clinical judgment to differentiate between temporary changes caused by an acute illness and potential indicators of underlying chronic conditions. Understanding the patient’s current health status helps avoid misdiagnosis or unnecessary further testing.
When to Proceed or Reschedule
The decision to proceed with or reschedule blood work when feeling unwell depends on the nature of the illness and the purpose of the test. For minor illnesses, such as a common cold, rescheduling may not always be necessary, but informing the doctor remains important. The impact of a mild illness on routine tests might be minimal or can be readily accounted for by the healthcare provider.
For moderate to severe illnesses, discussing rescheduling with the doctor is advisable. These conditions are more likely to cause significant alterations in blood test results, which could lead to misinterpretation or additional investigations. The urgency of the test also plays a role in this decision. If the blood work is for an urgent diagnosis, proceeding might be necessary to guide treatment. Conversely, if the tests are part of a routine check-up or for monitoring a stable chronic condition, rescheduling until after recovery can provide more accurate baseline results. Ultimately, consult with the ordering physician or healthcare provider.