4 Hepatic, Cardiac, and Endocrine Studies

Interpret results in context

Laboratory results need to be interpreted in relation to the patient, the assay, and the clinical situation. Compare each result with the laboratory reference interval on the patient’s report and with prior results when available. A result outside its interval is not, by itself, a diagnosis.

For critical or rapidly changing results, promptly assess the patient, report findings through the facility’s escalation pathway, and carry out authorized orders or protocols. If the patient is unstable, do not delay escalation while waiting for a routine repeat test.

Recognize liver-test patterns

ALT and AST are markers of hepatocellular injury. When their elevations are marked and alkaline phosphatase (ALP) is only mildly elevated, the pattern suggests predominantly hepatocellular injury. The size of an aminotransferase elevation does not, by itself, measure the extent of liver damage.

A disproportionately elevated ALP with increased direct bilirubin is a cholestatic pattern, which can occur when bile formation or flow is impaired. Correlate results with symptoms such as jaundice, dark urine, or pale stools; report concerning changes and anticipate further evaluation. Because ALP can also come from bone, other results and the clinical picture help identify its source.

Respond to acute liver concerns

New confusion with acute liver-test abnormalities and a prolonged INR requires urgent evaluation. Promptly assess the patient and escalate the change in mental status and abnormal INR to the responsible clinician or rapid-response team according to the patient’s condition and facility policy. Prepare for urgent orders or transfer if directed.

This combination can indicate acute liver failure. INR may reflect impaired hepatic clotting-factor synthesis, but it is not a reliable stand-alone measure of bleeding risk in cirrhosis.

Interpret troponin results

Troponin indicates myocardial injury, but an elevated value alone does not establish its cause or prove myocardial infarction. A rise or fall in serial values, symptoms, ECG findings, and assay-specific limits help determine its significance.

With new chest pressure, an initial high-sensitivity troponin below the assay’s upper reference limit followed by a rising result above it may indicate acute myocardial injury. With compatible symptoms and other clinical evidence, this raises concern for myocardial infarction. Promptly assess symptoms and vital signs, obtain or facilitate an ECG according to the chest-pain pathway, notify the clinician immediately, and follow the ordered serial-testing protocol. An early result may be negative, and interpretation depends on the assay, timing, ECG, and clinical presentation.

Troponin can be elevated without typical chest pain, including in patients with sepsis or kidney disease. Do not dismiss an abnormal result or assume it confirms myocardial infarction. Correlate it with symptoms, ECG, serial values, and the patient’s condition; CK-MB is not stated as a required confirmation test.

Use BNP with clinical findings

An elevated BNP can support heart failure as a cause of shortness of breath, but it is not diagnostic by itself. Kidney dysfunction and some lung or other heart conditions can also raise natriuretic peptide levels, so interpretation requires clinical context and often additional testing.

Assess respiratory status, oxygenation, vital signs, and signs of fluid overload. Report deterioration promptly.

Interpret thyroid results

A high TSH with a low free T4 is generally consistent with primary hypothyroidism. Interpret TSH alongside thyroid hormone results and clinical context; pregnancy, age, and serious illness can affect results. Review symptoms and medications, report the result as appropriate, and anticipate clinician-directed follow-up.

Recognize possible adrenal crisis

Low morning cortisol together with unexplained hypotension, hyponatremia, and hyperkalemia raises concern for adrenal insufficiency. Hypotension makes prompt escalation for urgent evaluation and treatment the priority. If adrenal crisis is suspected, do not wait for confirmatory testing.

A low morning cortisol can be suggestive, but its interpretation depends on timing, assay, and clinical context. Stimulation testing may be used when the patient is stable enough.