Lithium (Li) is normally found in hair at very low levels. Hair Li correlates with high dosage of Li carbonate in patients treated for Affective Disorders. However, the clinical significance of low hair Li levels is not certain at this time. Thus, hair Li is measured primarily for research purposes. Anecdotally, clinical feedback to DDI consultants suggests that low level Li supplementation may have some beneficial effects in patients with behavioral/emotional disorders. Li occurs almost universally in water and in the diet; excess Li is rapidly excreted in urine.

Lithocholic acid (LCA) is a bile acid formed from chenodeoxycholate by bacterial action, usually conjugated with glycine or taurine. It acts as a detergent to solubilize fats for absorption and is itself absorbed.

The Liver Fraction on Labcorp's Alkaline Phosphatase (ALP) Isoenzyme Panel refers to the specific portion of alkaline phosphatase that originates from the liver. This isoenzyme is measured to help assess liver function and diagnose liver-related disorders. Elevated levels of the liver fraction may indicate conditions such as liver disease, bile duct obstruction, or cholestasis. The ALP isoenzyme panel uses electrophoresis or other specialized techniques to differentiate between the liver, bone, and intestinal isoenzymes of alkaline phosphatase, providing critical insight into the source of elevated ALP levels. By accurately identifying the liver fraction, healthcare providers can better understand the underlying cause of liver dysfunction and determine appropriate treatment strategies.

Liver-Kidney Microsome IgG antibody (anti-LKM), as detected by indirect immunofluorescent antibody (IFA) techniques, may be observed in patients with autoimmune hepatitis type 2 (AIH-2), AIH-2 associated with autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED), viral hepatitis C or D, and some forms of drug-induced hepatitis. This IFA does not differentiate among the four types of LKM antibodies (LKM-1, LKM-2, LKM-3, and a fourth type that recognizes CYP1A2 and CYP2A6 antigens). Of these, anti-LKM-1 (cytochrome P450IID6) IgG antibodies are considered specific for AIH-2.

These antibodies target a human body’s produced enzyme called cytochrome P450 2D6, a protein found primarily in liver cells which catalyze many reactions involved in drug metabolism. The development of the LKM antibodies is strongly associated with type 2 autoimmune hepatitis.

Liver Kidney Microsomal (LKM-1) Antibody (IgG)

The presence of LKM-1 antibodies can be used in conjunction with clinical findings and other laboratory tests to aid in the diagnosis of autoimmune liver diseases such as autoimmune hepatitis (AIH-2).

Glutenin is a major protein found in wheat and constitutes about 47% of its protein content. Glutenin is responsible for the strength and elasticity of dough. The main types of glutenin are the LMW (low molecular weight) and the HMW (high molecular weight) glutenin.

HMW glutenin has been associated with Celiac disease, asthma and Atopic dermatitis.

LMW Glutenin has been associated with Celiac disease, asthma, Atopic dermatitis, Urticaria and Anaphylaxis.

The Lobster marker measures IgG antibodies to proteins found in lobster. Results are reported as none detected, very low, low, moderate, or high. These levels reflect immune exposure and recognition rather than a true shellfish allergy. Interpretation should consider symptoms, frequency of shellfish intake, and overall immune health.

Locust bean gum, also known as carob bean gum, comes from the carob seeds of the carob tree, grown in the Mediterranean. It is a hydrocolloid used in food as a thickener, stabilizer and emulsifier.

Locust bean gum is used as a stabilizer, thickener, and fat replacer in foods, and also as an adjunct gelling agent and texturizer to other hydrocolloids such as carrageenan.

Long chain fatty acids are a fecal fat. Fecal fats also include triglycerides, cholesterol and phospholipids. They are derived predominately from the dietary ingestion of fat, and provide important clues about digestion and absorption.

Long chain fatty acids are a fecal fat. Fecal fats also include triglycerides, cholesterol and phospholipids. They are derived predominately from the dietary ingestion of fat, and provide important clues about digestion and absorption.

LDL-3 is one of the subfractions of Low-Density Lipoprotein (LDL) — often referred to as “bad cholesterol.” LDL particles transport cholesterol through your bloodstream, but not all LDL particles are the same.

LDL is made up of different particle sizes and densities, classified from LDL-1 (large, buoyant) to LDL-7 (small, dense).

• Larger LDL particles (LDL-1, LDL-2) are considered less harmful.

• Smaller, denser LDL particles (LDL-3 and beyond) are more atherogenic, meaning they are more likely to promote plaque buildup in arteries.

Elevated LDL-3 levels suggest a shift toward smaller, denser LDL particles, which are more easily oxidized and can penetrate the artery wall — a key early step in atherosclerosis.

LDL-4 is one of the small, dense subfractions of Low-Density Lipoprotein (LDL) — the lipoprotein commonly referred to as “bad cholesterol.”

LDL particles vary in size and density, ranging from LDL-1 (large and buoyant) to LDL-7 (very small and dense).

• Larger LDL particles (LDL-1, LDL-2) are considered less harmful.

• Smaller, denser LDL particles (LDL-3, LDL-4, and beyond) are more atherogenic, meaning they have a greater tendency to promote plaque buildup in the arteries.

When LDL-4 is elevated, it indicates a shift toward a more atherogenic (plaque-forming) lipid profile, even if total LDL cholesterol appears normal.