Turnaround time is defined as the usual number of days from the date of pickup of a specimen for testing to when the result is released to the ordering provider. In some cases, additional time should be allowed for additional confirmatory or additional reflex tests. Testing schedules may vary.
Alanine aminotransferase (ALT) is an intracellular enzyme primarily found in the liver, with lower concentrations in the kidneys, heart, and skeletal muscle. It plays a key role in amino acid metabolism by catalyzing the conversion of alanine and α-ketoglutarate to pyruvate and glutamate. In clinical practice, ALT is widely used as a sensitive marker of hepatocellular injury. When liver cells are damaged or destroyed, ALT is released into the bloodstream, resulting in elevated serum levels.
ALT testing is commonly included in liver function panels and comprehensive metabolic panels to assess liver integrity. Any condition that compromises hepatocyte membrane integrity—such as inflammation, necrosis, or apoptosis—can lead to significant ALT elevation. The Liver plays a central role in metabolism, digestion, detoxification, and elimination of endogenous and exogenous substances. It processes blood from the gastrointestinal tract, transforming and storing nutrients including amino acids, glucose, lipids, vitamins, and minerals. The liver also synthesizes most major plasma proteins (excluding immunoglobulins and von Willebrand factor) and plays a critical role in maintaining glucose homeostasis via glycogen storage and gluconeogenesis. In lipid metabolism, the liver is the primary site for cholesterol, triglyceride, and lipoprotein synthesis, as well as bile acid production, which aids in fat digestion and absorption of fat-soluble vitamins. It also serves as the primary site for biotransformation—converting lipophilic compounds, such as drugs and toxins, into water-soluble forms for elimination. Additionally, the liver regulates hormone metabolism and contributes to the synthesis of several hormones and hormone precursors, including insulin-like growth factor 1 (IGF-1), angiotensinogen, hepcidin, thrombopoietin, erythropoietin, and 25-hydroxyvitamin D.
Despite its wide-ranging functions, the liver has a remarkable reserve capacity. Significant liver injury may occur before symptoms arise or functional impairments are detectable. For this reason, liver damage is often identified through laboratory testing rather than clinical presentation.
It is noted that ALT elevation is a sensitive but nonspecific indicator of liver cell injury. While it signifies hepatocellular damage, it does not identify the underlying cause. Common causes of elevated ALT include:
Alcohol-related liver disease
Non-alcoholic fatty liver disease (NAFLD) and non-alcoholic steatohepatitis (NASH)
Chronic viral hepatitis (hepatitis B and C)
Autoimmune hepatitis
Drug- or supplement-induced liver injury
Other less common causes include hemochromatosis, acute viral infections, vascular disorders affecting the liver, and various genetic conditions.
In cases of chronic liver injury, ongoing inflammation may lead to fibrosis, and over time, cirrhosis. Inflammatory cytokines can alter hepatic protein synthesis, serving as indirect markers of systemic or hepatic inflammation. Additionally, certain proteins may be overproduced during liver regeneration or in neoplastic processes, offering further insight into liver pathology. Given its sensitivity and accessibility, ALT remains a valuable tool in detecting liver injury. However, interpretation should always consider the clinical context and may require further diagnostic evaluation to determine the specific cause and extent of liver dysfunction.
References
Lala V, Zubair M, Minter DA. Liver Function Tests. [Updated 2023 Jul 30]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK482489/
Statement on Medical Necessity
All ordered tests should be medically necessary for the diagnosis or detection of disease, illness, impairment, symptom, syndrome, or disorder and the results should be used in the medical management and treatment decisions for the patient. Solaris requires ICD-10 codes with each order for lab testing and both the tests ordered and the diagnosis should be documented in the provider’s medical record for the patient. The United States Department of Health and Human Services, Office of Inspector General, takes the position that a provider who orders medically unnecessary tests may be subject to civil penalties.
Panels and Profiles
Solaris offers Providers the convenience of ordering test combinations in a group at times with the flexibility to choose appropriate test(s) for individual patients. Providers should only order those tests that he or she believes are medically necessary for each patient, and a lesser inclusive profile or individual tests should be ordered if not all tests in the test combination/profile are medically necessary. All tests offered in a test combination/profile may be ordered separately as individual tests. Solaris encourages clients to contact their Solaris representative if the testing configurations shown do not meet individual needs for any reason, or if some other combination of procedures is needed.
CPT Codes
CPT Codes listed are in accordance with Current Procedural Terminology, a publication of the American Medical Association. CPT codes are the responsibility of the billing party and are listed here for informational purposes. Correct coding may vary from one carrier to another. Solaris may bill specific carriers using codes other than what is shown.
For questions or inquiries related to testing please reach out to
customerservice@solarisdx.com or contact us by phone at (844) 550-0308.
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