Bilirubin is a waste byproduct of the breakdown of red blood cells. Yellow in coloration, bilirubin is filtered out of the blood by the liver and excreted in stool by the intestines. Bilirubin tests are done when a disease or blockage of the liver is suspected. Direct bilirubin differs from indirect bilirubin in that it is bound to a sugar and is therefore water soluble. 

The Indirect Bilirubin test measures how much bilirubin is in your blood. It originates from the breakdown of hemoglobin in the red blood cells, but must be removed by your liver. 

What is Bilirubin

Bilirubin is a yellowish substance. Bilirubin is made in the body when the hemoglobin protein in old red blood cells is broken down. The breakdown of old cells is a normal, healthy process. Bilirubin is found in bile, a fluid your liver makes that helps you digest food. Bilirubin is stored in the gallbladder and is involved in digesting food. Most bilirubin is eliminated in the feces or urine. Elevated bilirubin levels may indicate certain diseases. It is responsible for the yellow color of bruises and the yellow discoloration in jaundice. Its subsequent breakdown products, such as stercobilin, cause the brown color of feces. A different breakdown product, urobilin, is the main component of the straw-yellow color in urine. If your liver is healthy, it will remove most of the bilirubin from your body. If your liver is damaged, bilirubin can leak out of your liver and into your blood. When too much bilirubin gets into the bloodstream, it can cause jaundice, a condition that causes your skin and eyes to turn yellow. Signs of jaundice, along with a bilirubin blood test, can help your health care provider find out if you have liver disease.

Bilirubin is primarily derived from metabolism of hemoglobin. Only conjugated bilirubin is excreted into the urine and normally only trace amounts can be detected in urine.

Bilophila Wadsworthia is a gram negative, anaerobic, sulfidogenic bacterium resistant to β-lactam antibiotics. This pathobiont is commonly found in patients with appendicitis and it has been associated to the Western diet (high in fats and animal proteins), as well as severe malnutrition. A recent study in animals showed that a high fat diet stimulates the growth of B. Wadsworthia, which causes inflammation, dysfunction in the intestinal barrier and bile acid metabolism, hepatic steatosis and dysfunctional glucose metabolism. Interestingly, the co-administration of a probiotic strain (Lactobacillus rhamnoses) reduces the generated inflammation and limits the metabolic impairment.

Bilophila wadsworthia is a sulfate-reducing bacterium that naturally occurs in the human gut microbiome, typically in small quantities. This anaerobic, gram-negative bacillus was first isolated in 1989 and is known for its ability to thrive in bile-rich environments. While B. wadsworthia is present in 50-60% of healthy individuals, an overgrowth of this species has been associated with various health concerns. It produces hydrogen sulfide, which in excess can contribute to gut inflammation and has been linked to conditions such as inflammatory bowel disease, irritable bowel syndrome, and colorectal cancer. B. wadsworthia's growth is particularly stimulated by diets high in saturated fats and taurine-rich foods like meat and dairy products. In controlled studies, this bacterium has been shown to exacerbate metabolic dysfunctions in mice fed a high-fat diet, leading to increased inflammation, intestinal barrier dysfunction, and glucose dysregulation. The presence and abundance of B. wadsworthia in a BiomeFX report may provide insights into potential gut dysbiosis and associated health risks, especially in the context of dietary habits and metabolic health.

Biotin is required for proper metabolism of fats and carbohydrates. Biotin-dependent enzymes catalyze the addition of carboxyl groups (COO-) from bicarbonate, for use in fatty acid biosynthesis, gluconeogenesis, lipogenesis, propionate metabolism, and leucine catabolism.

Biotin, also known as Vitamin B7, is a water-soluble B-complex vitamin that plays a critical role in various metabolic processes and is commonly included in blood panel tests to assess nutritional status. It acts as a coenzyme for carboxylase enzymes, pivotal in the synthesis of fatty acids, amino acids, and the generation of glucose from non-carbohydrate sources. Biotin is essential for the proper functioning of the nervous system and plays a role in maintaining skin, hair, and mucous membrane health.

Bismuth is found in alloys, catalysts, cosmetics, paints, magnets, ceramics, pharmaceuticals, x-ray contrast media,
and semiconductors. Bismuth is generally non-toxic, although very high levels may cause nausea, vomiting, and diarrhea.
Renal, neurological, and hematological problems have been associated with bismuth toxicity. Hair is not a sensitive
specimen for bismuth toxicity; blood and urine are most commonly used.

Bismuth is found in alloys, catalysts, cosmetics, paints, magnets, ceramics, pharmaceuticals, x-ray contrast media,
and semiconductors. Bismuth is generally non-toxic, although very high levels may cause nausea, vomiting, and diarrhea.
Renal, neurological, and hematological problems have been associated with bismuth toxicity. Hair is not a sensitive
specimen for bismuth toxicity; blood and urine are most commonly used.

Used in alloys, electronics, batteries, crystal ware, cosmetics, flame retardants,and in antimicrobial therapy (H. pylori), antiseptic dressings, paraffin paste. Bismuth medical therapies exhibit high therapeutic effects and little side effects, though over-dosage can cause toxicity.

Very limited absorption in the GI tract. When absorbed, it binds mainly to transferrin and lactoferrin, interacts with enzymes due to a high affinity to cysteine residues, blocking the active site. Can accumulate in the kidney, lung, spleen, liver, brain, and muscles, while being eliminated in urine and feces via bile and intestinal secretions.

Fecal bismuth (Bi) provides an estimate of a recent oral exposure to the element. Bi is a non-essential element of relatively low toxicity. Absorption is dependent upon solubility of the Bi compound, with insoluble Bi excreted in the feces while soluble forms are excreted primarily in the urine. Sources of Bi include: cosmetics (lipstick), Bi containing medications such as ranitidine Bi-citrate, antacids (Pepto-
Bismol), pigments used in colored glass and ceramics, dental cement, and dry cell battery electrodes.

Several organometallic Bi compounds are used for bactericidal and fungicidal applications.

Symptoms of moderate Bi toxicity include constipation or bowel irregularity, foul breath, blue/black gum line, and malaise. Unusually high levels of Bi retention in the body may result in nephrotoxicity (nephrosis, proteinurea) and neurotoxicity (tremor, memory loss, monoclonic jerks, dysarthria, dementia). Urine elements analysis may be used to corroborate Bi absorption for a period of days or a few weeks after
the exposure.

Used in alloys, electronics, batteries, crystal ware, cosmetics, flame retardants,and in antimicrobial therapy (H. pylori), antiseptic dressings, paraffin paste. Bismuth medical therapies exhibit high therapeutic effects and little side effects, though over-dosage can cause toxicity.

Very limited absorption in the GI tract. When absorbed, it binds mainly to transferrin and lactoferrin, interacts with enzymes due to a high affinity to cysteine residues, blocking the active site. Can accumulate in the kidney, lung, spleen, liver, brain, and muscles, while being eliminated in urine and feces via bile and intestinal secretions.

Bismuth is a heavy, brittle metal with a white, silver-pink hue, typically found in small amounts in the earth's crust and often used in various industrial, cosmetic, and pharmaceutical applications, such as in the manufacturing of low-melting alloys, cosmetics, and some medications, particularly those used for gastrointestinal issues. In the context of a hair test, the presence of bismuth can indicate exposure to these products or environmental sources. While trace amounts of bismuth are generally considered non-toxic to humans, elevated levels can be a cause for concern.

Bisphenol A (BPA) is a xenoestrogen, exhibiting estrogen-mimicking, hormone-like properties that raise concern about its suitability in some consumer products and food containers. Bisphenol A (BPA) is an organic synthetic compound and it is a starting material for the synthesis of plastics, primarily certain polycarbonates and epoxy resins, as well as some polysulfones and certain niche materials. BPA is an endocrine-disrupting chemical that has been found to bind to both of the nuclear estrogen receptors. A recent exposure to plastic that released excessive amounts of BPA into a food or a beverage could be identified by high levels of urinary BPA.