VEGF
VEGF Overview Vascular endothelial growth factor (VEGF) measures circulating levels of this family of signaling proteins that stimulate angiogenesis, vascular permeability, and endothelial cell growth. VEGF-A, the predominant isoform, binds VEGFR-2 receptors promoting tumor vascularization and pathological neovascularization. Elevated levels indicate cancer progression, retinopathy, or inflammatory conditions, while low levels lack established clinical significance; primarily […]
Vitamin B6
Vitamin B6 Overview Vitamin B6 measures serum levels of pyridoxal 5'-phosphate (PLP), the active coenzyme form essential for amino acid metabolism, neurotransmitter synthesis, and heme production. It functions as a cofactor for over 100 enzymatic reactions including glycogenolysis, gluconeogenesis, and homocysteine metabolism. Low levels indicate poor dietary intake, malabsorption, alcoholism, or drug-induced deficiency causing peripheral […]
Vitamin D
Vitamin D Overview Vitamin D, measured as 25-hydroxyvitamin D [25(OH)D] in serum, assesses nutritional status and reflects production from skin UVB exposure or dietary/supplemental intake. It regulates calcium/phosphate homeostasis, bone mineralization, immune function, and cellular growth through nuclear receptor activation. Low levels indicate deficiency causing rickets/osteomalacia or osteoporosis risk, while high levels suggest toxicity; clinically […]
Vitamin B12
Vitamin B12 Overview Vitamin B12 (cobalamin) measures serum levels of this essential water-soluble vitamin required for red blood cell formation, myelin synthesis, and DNA production via methylmalonyl-CoA mutase and methionine synthase activation. It is obtained exclusively from animal products and absorbed via intrinsic factor in the terminal ileum. Low levels indicate pernicious anemia, malabsorption, vegan […]
Wilson Disease Copper Marker
Wilson Disease Copper Marker Overview The Wilson disease copper marker typically refers to non-ceruloplasmin-bound copper (free copper) in serum, calculated as total serum copper minus ceruloplasmin-bound copper. Copper is an essential trace element involved in enzymatic reactions, but excess free copper accumulation due to ATP7B gene mutations in Wilson disease leads to toxic effects in […]
Wnt Signaling Proteins
Wnt Signaling Proteins Overview Wnt signaling proteins are a family of secreted glycoproteins that regulate key cellular processes including proliferation, differentiation, migration, and polarity through canonical (β-catenin-dependent) and non-canonical pathways. They bind to cell surface receptors such as Frizzled and LRP5/6, modulating gene transcription, embryonic development, tissue homeostasis, and stem cell maintenance. Abnormal levels or […]
Willebrand Factor
Willebrand Factor Overview Von Willebrand factor (VWF) is a large multimeric glycoprotein involved in hemostasis that mediates platelet adhesion to damaged endothelium and serves as a carrier protein for coagulation factor VIII in plasma. It is synthesized primarily by endothelial cells and megakaryocytes and stored in Weibel‑Palade bodies and platelet α‑granules. Elevated VWF levels can […]
Whole Blood Viscosity
Whole Blood Viscosity Overview Whole blood viscosity measures the resistance to flow of whole blood through vessels, determined primarily by hematocrit, plasma viscosity, red cell deformability, and aggregation. It reflects rheological properties influencing microvascular perfusion and cardiovascular hemodynamics. Elevated levels indicate hyperviscosity syndrome from polycythemia, multiple myeloma, or Waldenström macroglobulinemia, while low levels lack clinical […]
WBC Count
WBC Count Overview WBC count measures total circulating leukocytes per microliter of blood, reflecting systemic immune response and bone marrow production. White blood cells include neutrophils, lymphocytes, monocytes, eosinophils, and basophils, each mediating specific immune functions against infection, inflammation, or allergy. Elevated counts (leukocytosis) indicate infection, inflammation, leukemia, or steroid use, while low counts (leukopenia) […]
Xanthurenic Acid
Xanthurenic Acid Overview Xanthurenic acid is a tryptophan metabolite produced via the kynurenine pathway, specifically reflecting pyridoxal 5'-phosphate (vitamin B6)-dependent kynureninase activity. It serves as a biomarker of vitamin B6 nutritional status and functional deficiency, as B6 is required for its conversion to 3-hydroxykynurenine. Elevated urinary levels after a tryptophan load indicate B6 deficiency, while […]
Xylulose
Xylulose Overview Xylulose is a five-carbon ketopentose sugar and key intermediate in the pentose phosphate pathway, primarily measured as xylulose-5-phosphate or its dephosphorylated form in metabolic studies. It plays a critical role in carbohydrate metabolism, nucleotide synthesis, and NADPH production for antioxidant defense and lipid biosynthesis. Elevated urinary xylulose indicates essential fructosuria, a benign metabolic […]
X-Linked Immunoglobulin Marker
X-Linked Immunoglobulin Marker Overview X-Linked Immunoglobulin Marker typically refers to IgM or related immunoglobulin levels measured in the context of X-linked agammaglobulinemia (XLA), a primary immunodeficiency caused by BTK gene mutations. IgM is a pentameric antibody produced by B cells that provides early immune defense against pathogens through complement activation and agglutination. Low or absent […]
Prolactin
Prolactin Overview Prolactin measures a peptide hormone secreted by anterior pituitary lactotroph cells that primarily stimulates mammary gland development and milk production during pregnancy and lactation. It also influences reproductive function, immune regulation, and osmoregulation through widespread tissue receptors. Elevated levels (hyperprolactinemia) indicate prolactinoma, stalk compression, medications, or hypothyroidism; low levels rarely cause clinical symptoms. […]
Platelet Count
Platelet Count Overview Platelet count measures the number of platelets (thrombocytes) circulating in blood, typically 150-450 × 10⁹/L, essential for hemostasis, clot formation, and vascular repair. Platelets aggregate at injury sites under von Willebrand factor and collagen guidance, releasing granule contents to activate coagulation. Elevated counts (thrombocytosis) indicate inflammation, iron deficiency, or myeloproliferative neoplasms; low […]
Q Fever Antibody
Q Fever Antibody Overview Q fever antibody measures serologic response to Coxiella burnetii antigens, primarily phase I and phase II IgG and IgM, indicating past or current infection with this obligate intracellular bacterium. These antibodies reflect immune recognition of the pathogen responsible for acute fever, pneumonia, or chronic endocarditis. Elevated phase II IgM/IgG suggests acute […]
Quinine Level
Quinine Level Overview Quinine level measures the concentration of quinine, an alkaloid derived from cinchona bark, in blood to assess therapeutic drug monitoring and toxicity risk. It functions primarily as an antimalarial agent by interfering with parasite protein synthesis and has secondary antiarrhythmic and muscle relaxant effects. High levels may indicate overdose, renal impairment, or […]
Quinolinate
Quinolinate Overview Quinolinate, also known as quinolinic acid, is a neuroactive metabolite in the kynurenine pathway of tryptophan catabolism, measured primarily in cerebrospinal fluid, plasma, or urine. It functions as a potent NMDA receptor agonist, contributing to excitotoxicity and neuroinflammation in the central nervous system. Elevated levels indicate neuroinflammatory conditions, neurodegeneration, or infections like HIV […]
Quinolinic Acid
Quinolinic Acid Overview Quinolinic acid is an endogenous metabolite of the kynurenine pathway from tryptophan degradation, measured in cerebrospinal fluid (CSF), plasma, or urine as a marker of neuroinflammation and excitotoxicity. It acts as an agonist of NMDA receptors, contributing to neuronal damage in neurodegenerative and inflammatory conditions. Elevated levels indicate central nervous system inflammation, […]
Q10 (Coenzyme Q10)
Q10 (Coenzyme Q10) Overview Coenzyme Q10 (CoQ10), measured in plasma or serum, is a lipid-soluble antioxidant and essential cofactor in the mitochondrial electron transport chain, facilitating ATP production. It protects cell membranes from oxidative damage and supports cardiovascular and energy metabolism functions. Low levels may indicate mitochondrial disorders, statin use, heart failure, or aging, while […]
RANTES (CCL5)
RANTES (CCL5) Overview RANTES (regulated on activation, normal T cell expressed and secreted), also known as CCL5, measures circulating levels of this CC chemokine produced by T cells, macrophages, and platelets. It functions to recruit immune cells including T cells, eosinophils, and basophils to sites of inflammation through CCR1, CCR3, and CCR5 receptor binding. Elevated […]