What it is: A potassium blood test measures the level of potassium, an electrolyte essential for heart, nerve, and muscle function, in the blood.
Why it's ordered: Ordered as part of an electrolyte or metabolic panel to monitor kidney disease, heart conditions, or diuretic use, or when symptoms like muscle weakness or irregular heartbeat raise concern.
What it detects: Potassium is tightly regulated by the kidneys; both high and low levels can affect heart rhythm significantly, making this one of the more urgent electrolytes to correct when abnormal.
Collection & prep: A standard blood draw from a vein in the arm. Sample handling matters — hemolysis (cell rupture during or after the draw) can falsely raise results, so repeat testing is sometimes needed to confirm an abnormal value.
Results:
High (hyperkalemia) – can cause dangerous heart rhythm changes; linked to kidney disease, certain medications, or tissue injury
Low (hypokalemia) – can cause muscle weakness or heart rhythm changes; linked to vomiting, diarrhea, or diuretic use
Normal – heart and muscle function appear well-supported
Possible complications of a potassium imbalance: Significantly abnormal potassium levels can cause life-threatening heart arrhythmias, so markedly high or low results — especially with symptoms like palpitations or severe weakness — warrant prompt medical attention.
Quick Guide: Prostate-specific antigen, total (PSA-T) Blood Test
What it is: A total PSA (prostate-specific antigen) test measures the level of PSA, a protein produced by normal and cancerous prostate cells, in the blood.
Why it's ordered: Used to screen for prostate cancer, typically starting around age 50 (or earlier with elevated risk), and to evaluate symptoms suggestive of prostate problems or monitor prostate cancer treatment.
What it detects: PSA levels rise with prostate cancer, but also with benign conditions like an enlarged prostate (BPH) or prostatitis, so PSA is a marker of prostate activity generally rather than a cancer-specific marker.
Collection & prep: A standard blood draw from a vein in the arm, often paired with a digital rectal exam. Ejaculation or vigorous exercise shortly before the test can temporarily raise PSA, so providers may advise avoiding these beforehand.
Results:
Elevated – may prompt additional testing (e.g., percent-free PSA, imaging, or biopsy) to assess prostate cancer risk; normal PSA rises somewhat with age
Normal – lower likelihood of significant prostate disease, though it doesn't fully rule out cancer
Possible complications: PSA screening can lead to overdiagnosis or false positives from non-cancerous causes, which is why it's generally used as one part of a broader diagnostic approach rather than as a standalone test.
What it is: A total protein test measures the combined amount of all proteins — mainly albumin and globulins — in the blood.
Why it's ordered: Ordered as part of a liver panel or comprehensive metabolic panel to help evaluate liver or kidney function, nutritional status, or certain immune and bone marrow conditions.
What it detects: Since the liver makes albumin and globulins support immune function, abnormal total protein can point to liver disease, kidney disease (protein loss through urine), malnutrition, or conditions affecting antibody-producing cells.
Collection & prep: A standard blood draw from a vein in the arm, typically as part of a broader metabolic or liver panel. No special preparation is usually required.
Results:
Low – can reflect liver disease, kidney protein loss, malnutrition, or inflammation
High – can reflect chronic inflammation, dehydration, or certain conditions affecting antibody production
Normal – roughly 6.3–8.0 g/dL, varying by lab
Possible complications: Total protein alone doesn't pinpoint a cause; abnormal results are usually followed by breaking the value down into albumin and globulin fractions to narrow down whether the liver, kidneys, or immune system is involved.
What it is: A total protein test measures the combined amount of all proteins — mainly albumin and globulins — in the blood.
Why it's ordered: Ordered as part of a liver panel or comprehensive metabolic panel to help evaluate liver or kidney function, nutritional status, or certain immune and bone marrow conditions.
What it detects: Since the liver makes albumin and globulins support immune function, abnormal total protein can point to liver disease, kidney disease (protein loss through urine), malnutrition, or conditions affecting antibody-producing cells.
Collection & prep: A standard blood draw from a vein in the arm, typically as part of a broader metabolic or liver panel. No special preparation is usually required.
Results:
Low – can reflect liver disease, kidney protein loss, malnutrition, or inflammation
High – can reflect chronic inflammation, dehydration, or certain conditions affecting antibody production
Normal – roughly 6.3–8.0 g/dL, varying by lab
Possible complications: Total protein alone doesn't pinpoint a cause; abnormal results are usually followed by breaking the value down into albumin and globulin fractions to narrow down whether the liver, kidneys, or immune system is involved.
Quick Guide: Red blood cell (RBC) count Blood Test
What it is: A red blood cell (RBC) count measures the number of red blood cells in a blood sample, typically as part of a complete blood count.
Why it's ordered: Ordered alongside a CBC to help diagnose anemia or polycythemia, or to evaluate symptoms like fatigue, pale skin, or shortness of breath.
What it detects: A low RBC count generally reflects anemia from blood loss, nutritional deficiency, or bone marrow problems; a high count can reflect dehydration, lung or heart disease, or a bone marrow disorder that overproduces red cells.
Collection & prep: A standard blood draw from a vein in the arm, as part of a CBC. No special preparation is required.
Results:
Low – suggests anemia; interpreted alongside hemoglobin, hematocrit, and MCV to narrow the cause
High – suggests dehydration or excess red blood cell production
Possible complications of an abnormal count: RBC count is rarely interpreted alone — it's combined with hemoglobin, hematocrit, and red cell indices (like MCV) to characterize and narrow down the type of anemia or other condition present.
Quick Guide: Red blood cell (RBC) count Blood Test
What it is: A red blood cell (RBC) count measures the number of red blood cells in a blood sample, typically as part of a complete blood count.
Why it's ordered: Ordered alongside a CBC to help diagnose anemia or polycythemia, or to evaluate symptoms like fatigue, pale skin, or shortness of breath.
What it detects: A low RBC count generally reflects anemia from blood loss, nutritional deficiency, or bone marrow problems; a high count can reflect dehydration, lung or heart disease, or a bone marrow disorder that overproduces red cells.
Collection & prep: A standard blood draw from a vein in the arm, as part of a CBC. No special preparation is required.
Results:
Low – suggests anemia; interpreted alongside hemoglobin, hematocrit, and MCV to narrow the cause
High – suggests dehydration or excess red blood cell production
Possible complications of an abnormal count: RBC count is rarely interpreted alone — it's combined with hemoglobin, hematocrit, and red cell indices (like MCV) to characterize and narrow down the type of anemia or other condition present.
Quick Guide: Sequential multiple analyzer (SMA-6, 12, 20) Blood Test
What it is: SMA (sequential multiple analyzer, e.g. SMA-6, 12, or 20) is an older name for an automated blood chemistry panel — the number reflects how many substances the analyzer measured at once, similar to today's basic or comprehensive metabolic panel.
Why it's ordered: Historically ordered as a general health screening tool or to monitor existing conditions affecting the liver, kidneys, heart, muscles, or bones, in a single automated blood run.
What it detects: Depending on the panel size, an SMA can include glucose, kidney markers (BUN, creatinine), electrolytes (calcium, phosphorus), protein markers (total protein, albumin, globulin), cholesterol, liver enzymes (AST, ALT, ALP, bilirubin), and muscle markers (LDH, CK) — giving a broad snapshot across several organ systems.
Collection & prep: A standard blood draw from a vein in the arm. Fasting for 8–12 hours may be requested depending on which components are included.
Results:
Abnormal individual values – point toward a specific organ system (liver, kidney, heart, muscle, or bone) needing further evaluation
All values normal – no broad metabolic abnormality detected at the time of testing
Possible complications: As a broad screening panel, an SMA doesn't diagnose a specific condition on its own; abnormal individual components are typically followed up with more targeted testing.
What it is: SGOT (serum glutamic-oxaloacetic transaminase) is an older name for the AST (aspartate aminotransferase) test, which measures the same liver- and muscle-related enzyme in the blood.
Why it's ordered: Ordered to assess liver health, typically alongside SGPT/ALT in a liver panel, when a provider suspects liver damage or wants to evaluate other conditions affecting muscle or heart tissue.
What it detects: SGOT/AST leaks into the blood when liver cells (or other AST-containing tissues, like heart or skeletal muscle) are damaged. Comparing it with SGPT/ALT helps determine whether elevated enzymes point to liver-specific injury or a broader cause.
Collection & prep: A standard blood draw from a vein in the arm. No special preparation is typically required unless part of a larger fasting panel.
Results:
High – typically above 35 IU/L in adults; suggests damage to the liver or another AST-containing tissue
Normal – roughly 0–35 IU/L, though ranges vary by lab
Possible complications of liver or muscle damage: SGOT/AST alone can't pinpoint the source of damage; providers typically interpret it alongside SGPT/ALT and clinical symptoms to determine whether the cause is hepatic, cardiac, or muscular.
What it is: SGPT (serum glutamic-pyruvic transaminase) is an older name for the ALT (alanine aminotransferase) test, which measures the same liver enzyme in the blood.
Why it's ordered: Ordered to evaluate liver health, typically alongside SGOT/AST in a liver panel, when a provider suspects liver damage from hepatitis, fatty liver disease, medication effects, or alcohol use.
What it detects: SGPT/ALT leaks into the blood when liver cells are damaged. Because it's more concentrated in the liver than SGOT/AST, it's considered a fairly specific marker of liver injury.
Collection & prep: A standard blood draw from a vein in the arm. No special preparation is typically required unless part of a larger fasting panel.
Results:
High – typically above 45 IU/L in adults; suggests liver cell damage from hepatitis, fatty liver disease, or medication/alcohol effects
Normal – roughly 0–45 IU/L, though ranges vary by lab
Possible complications of liver damage: A single elevated SGPT/ALT doesn't diagnose a specific disease; it's usually interpreted alongside SGOT/AST, ALP, and GGT to narrow down the cause.
What it is: A sodium blood test measures the level of sodium, the main electrolyte controlling fluid balance outside the body's cells, in the blood.
Why it's ordered: Ordered as part of an electrolyte or metabolic panel to evaluate dehydration, fluid overload, or symptoms like confusion, seizures, or unexplained fatigue.
What it detects: Sodium levels reflect the balance between water and salt in the body rather than salt intake alone; abnormal levels can point to kidney disease, hormonal imbalances, or excessive fluid loss or intake.
Collection & prep: A standard blood draw from a vein in the arm, usually as part of a broader metabolic panel. No special preparation is typically required.
Results:
High (hypernatremia) – usually reflects dehydration or excess free water loss
Low (hyponatremia) – can reflect excess fluid retention, certain medications, or hormonal conditions
Normal – fluid balance appears stable
Possible complications of a sodium imbalance: Rapid or severe sodium shifts can cause confusion, seizures, or brain swelling, which is why very abnormal levels are corrected gradually and under medical supervision rather than all at once.
Statements made in the Clinical Manual have not been evaluated by the FDA. The products mentioned are not intended to diagnose, treat, cure or prevent any disease.
