Reticulocyte Count
Reticulocyte Count Overview Reticulocyte count measures the number of immature red blood cells (reticulocytes) in peripheral blood, expressed as a percentage or absolute count, reflecting bone marrow erythropoietic activity. Reticulocytes are young erythrocytes that mature over 1-2 days, serving as an indicator of recent red cell production in response to anemia or hemolysis. Elevated counts […]
Rheumatoid Factor
Rheumatoid Factor Overview Rheumatoid factor (RF) measures autoantibodies, primarily IgM, directed against the Fc portion of IgG immunoglobulins in serum. It reflects immune complex formation and B-cell activation relevant to autoimmune processes. Elevated levels may indicate rheumatoid arthritis, Sjögren’s syndrome, or other autoimmune conditions, while low levels are typical in healthy individuals; it is clinically […]
Renin
Renin Overview Renin is an enzyme secreted by the juxtaglomerular cells of the kidney that measures plasma activity or concentration as part of the renin-angiotensin-aldosterone system (RAAS), which regulates blood pressure and fluid balance. It cleaves angiotensinogen to produce angiotensin I, leading to vasoconstriction and aldosterone release. Elevated levels indicate renovascular hypertension, malignant hypertension, or […]
RBC Count
RBC Count Overview RBC count measures the number of red blood cells (erythrocytes) per unit volume of blood, typically reported as millions per microliter. Red blood cells contain hemoglobin and transport oxygen from lungs to tissues while removing carbon dioxide. Elevated counts (polycythemia) may indicate dehydration, smoking, high altitude, or polycythemia vera, while low counts […]
SAA (Serum Amyloid A)
SAA (Serum Amyloid A) Overview Serum amyloid A (SAA) measures circulating levels of this acute-phase protein primarily produced by hepatocytes in response to interleukin-6 and other cytokines during inflammation. It functions as an opsonin, participates in cholesterol transport during inflammation, and modulates immune responses. Elevated SAA levels indicate acute or chronic inflammation, infection, trauma, or […]
Serotonin
Serotonin Overview Serotonin (5-hydroxytryptamine, 5-HT) is a neurotransmitter derived from tryptophan that transmits nerve impulses, constricts blood vessels, regulates mood, and influences gastrointestinal motility and sleep-wake cycles. Over 90% of circulating serotonin is stored in platelets, with the remainder produced by enterochromaffin cells in the gut and brain neurons. Elevated levels, often due to serotonin-secreting […]
Serum Iron
Serum Iron Overview Serum iron measures the concentration of circulating iron bound to transferrin in blood, reflecting the amount of iron available for hemoglobin synthesis and other metabolic functions. Iron is essential for oxygen transport via hemoglobin and myoglobin, energy production, and DNA synthesis. Low levels indicate iron deficiency from blood loss, poor absorption, or […]
SHBG
SHBG Overview Sex hormone–binding globulin (SHBG) is a glycoprotein produced mainly by the liver that binds circulating sex steroids, especially testosterone and estradiol, thereby regulating their free (biologically active) fractions in blood. It plays an important role in modulating androgen and estrogen action at target tissues and is influenced by hormonal, metabolic, and liver status. […]
Sodium
Sodium Overview Sodium measures serum concentration of this major extracellular cation essential for maintaining osmotic pressure, fluid balance, nerve impulse transmission, and muscle contraction. It is primarily regulated by renal excretion under aldosterone and antidiuretic hormone control. Hyponatremia (low sodium) may indicate SIADH, heart failure, diuretics, or water intoxication, while hypernatremia (high sodium) suggests dehydration, […]
Transferrin
Transferrin Overview Transferrin measures serum glycoprotein that binds and transports iron from sites of absorption and storage to erythroid precursors for hemoglobin synthesis. It maintains iron homeostasis and delivers iron via transferrin receptor-mediated endocytosis. Low levels indicate iron deficiency, malnutrition, or chronic inflammation (negative acute phase reactant), while high levels suggest iron overload or genetic […]
Triglycerides
Triglycerides Overview Triglycerides measure circulating levels of this major dietary fat form, stored in adipose tissue and providing energy between meals through lipoprotein packaging. They comprise three fatty acids esterified to glycerol, transported primarily as very-low-density lipoprotein (VLDL) from liver. Elevated levels indicate metabolic syndrome, diabetes risk, or dietary excess, while low levels rarely cause […]
Troponin
Troponin Overview Troponin measures cardiac-specific proteins (troponin I or T) released into bloodstream following myocardial injury, serving as highly sensitive and specific biomarkers of cardiomyocyte damage. These regulatory proteins control actin-myosin interactions essential for cardiac muscle contraction. Elevated levels indicate acute myocardial infarction, myocarditis, heart failure exacerbation, or other cardiac injuries, while normal levels effectively […]
Lipoprotein(a)
Lipoprotein(a) Overview Lipoprotein(a), or Lp(a), measures the concentration of a low-density lipoprotein particle covalently bound to apolipoprotein(a), which structurally resembles plasminogen. Lp(a) promotes atherosclerosis by carrying cholesterol like LDL while inhibiting fibrinolysis through competitive binding to plasminogen receptors. Elevated Lp(a) levels, largely genetically determined, indicate increased risk for atherosclerotic cardiovascular disease, aortic stenosis, and thromboembolic […]
LDL Cholesterol
LDL Cholesterol Overview LDL cholesterol measures the concentration of low-density lipoprotein particles that primarily transport cholesterol from the liver to peripheral tissues. These lipoproteins deliver cholesterol for cell membrane synthesis and hormone production, but excess levels contribute to atherosclerotic plaque formation in arteries. High LDL cholesterol indicates increased cardiovascular risk, while low levels may reflect […]
Myeloperoxidase
Myeloperoxidase Overview Myeloperoxidase measures an enzyme stored in azurophilic granules of neutrophils and monocytes that generates hypochlorous acid and other reactive oxygen species for microbial killing during inflammation. It contributes to oxidative tissue damage in atherosclerosis, vasculitis, and acute coronary syndromes through endothelial dysfunction and plaque instability. Elevated levels indicate neutrophil activation in cardiovascular disease, […]
Methylmalonic Acid
Methylmalonic Acid Overview Methylmalonic acid (MMA) measures an intermediate metabolite of odd-chain fatty acid, isoleucine, and valine catabolism that accumulates when vitamin B12 is deficient or when methylmalonyl-CoA mutase is defective. Vitamin B12 serves as a cofactor for MMA conversion to succinyl-CoA, a Krebs cycle intermediate; deficiency impairs this step causing MMA accumulation. Elevated MMA […]
Monocytes
Monocytes Overview Monocytes measure the absolute number or percentage of circulating monocytes, a type of white blood cell that constitutes 2-8% of total leukocytes and differentiates into macrophages and dendritic cells in tissues. These cells participate in immune surveillance, phagocytosis of pathogens, antigen presentation, and cytokine production during inflammation. Elevated levels (monocytosis) indicate chronic infections, […]
Myoglobin
Myoglobin Overview Myoglobin measures an oxygen-binding heme protein found predominantly in cardiac and skeletal muscle cells that facilitates oxygen storage and transport within muscle tissue. During muscle injury, myoglobin is released into circulation where it can cause renal toxicity due to its rapid filtration and precipitation in renal tubules. Elevated levels indicate rhabdomyolysis, myocardial infarction, […]
Magnesium
Magnesium Overview Magnesium measures the concentration of this essential divalent cation primarily involved in enzymatic reactions, neuromuscular transmission, and structural roles in bones and ATP complexes. About 99% of body magnesium resides intracellularly or in bone; serum levels reflect only 1% of total body stores but indicate acute changes in magnesium balance. Low levels indicate […]
Non-HDL Cholesterol
Non-HDL Cholesterol Overview Non-HDL cholesterol measures the cholesterol content in all atherogenic lipoproteins (LDL + VLDL + IDL + lipoprotein(a)) calculated as total cholesterol minus HDL cholesterol. These particles transport cholesterol to peripheral tissues and contribute to atherosclerotic plaque formation; non-HDL-C reflects total atherogenic burden more comprehensively than LDL-C alone. Elevated levels indicate increased cardiovascular […]