diagnostilistests

Diagnostic tests, sometimes written as diagnostistests in informal contexts, are procedures and analyses used to determine whether a patient has a particular disease, condition, or physiological state. They serve to confirm or refute clinical hypotheses, stratify risk, monitor disease, and guide treatment decisions.

They encompass a broad range of modalities, including laboratory tests (blood chemistry, complete blood count, urinalysis), imaging studies (X-ray, CT, MRI, ultrasound), functional and physiologic tests (ECG, spirometry, audiometry, neurophysiological tests), microbiologic assays and cultures, genetic and molecular tests, and tissue-based methods such as biopsy and histopathology.

The usefulness of a diagnostic test is described by performance characteristics such as sensitivity, specificity, and predictive values. Clinicians also consider likelihood ratios, pretest probability, and post-test probability. The gold standard reference method is used to validate new tests and determine accuracy.

A typical process involves selecting tests based on symptoms and risk, collecting appropriate samples, processing in accredited laboratories, and interpreting results in the clinical context. Results are often integrated with history, exam findings, and imaging, with follow-up testing as needed to resolve uncertainty.

Quality assurance, standardization, and regulatory oversight ensure test reliability. Ethical considerations include informed consent when appropriate, privacy, and equitable access. Limitations include false positives and negatives, pre-analytical variables, timing relative to disease course, and cost.

Examples include common blood tests (glucose, lipid panel, troponin), infectious disease assays (PCR for viral RNA, antibody tests), genetic tests, imaging (CT, MRI), and tissue diagnosis (biopsy with histology).