Prostaglandin D2 (PGD2) is a bioactive lipid compound that plays a significant role in various physiological and pathological processes within the human body. It belongs to the family of prostaglandins, which are a group of physiologically active lipid compounds having diverse hormone-like effects in animals. PGD2 itself is produced primarily by mast cells, which are cells involved in the immune response, and it is derived from arachidonic acid through the action of the enzyme prostaglandin D synthase. This compound has several important roles, including the mediation of allergic responses and inflammation. In the context of allergies, PGD2 can cause symptoms such as bronchoconstriction and vasodilation. It's also involved in the regulation of sleep-wake cycles and acts as a neuromodulator in the brain.

Prostaglandins are lipid autacoids derived from arachidonic acid. They both sustain homeostatic functions and mediate pathogenic mechanisms, including the inflammatory response. 

Total Prostate Specific Antigen (TPSA) is a serine protease produced by prostate cells, primarily used as a biomarker for the screening and monitoring of prostate cancer. While elevated TPSA levels can indicate the presence of prostate cancer, they can also arise from benign conditions such as benign prostatic hyperplasia (BPH) and prostatitis. The TPSA test measures the total amount of PSA in the blood, which includes both free and protein-bound forms. Although TPSA is a valuable tool in early detection and management of prostate cancer, its specificity is limited, as elevated levels can occur in non-cancerous conditions. Therefore, healthcare providers often use additional tests, such as the free-to-total PSA ratio, to improve diagnostic accuracy and differentiate between benign and malignant prostate conditions.

The prostate-specific antigen (PSA) test measures the amount of PSA protein in your blood, which is produced by both normal and abnormal cells in the prostate gland. While higher PSA levels can be linked to prostate cancer, they can also result from non-cancerous conditions such as prostatitis, urinary tract infections, or benign prostate enlargement (BPH). Certain medications and recent activities like ejaculation or vigorous exercise can also influence results. There is no single “normal” PSA level—values often vary by age, race, and individual health factors. Instead, doctors look at trends over time, known as PSA velocity, to help determine whether further evaluation, such as imaging or biopsy, is needed.

Urine protein tests detect and/or measure protein being released into the urine. If the kidneys are damaged or compromised due to other conditions, they become less effective at filtering, causing detectable amounts of protein to spill over into the urine.

Protein C is a vitamin K-dependent plasma protein. 

Protein C helps control blood clotting. A lack of this protein or a problem with the function of this protein may cause blood clots to form in veins. The test is also used to screen relatives of people who are known to have protein C deficiency. It may also be done to find the reason for repeated miscarriages.

Protein S is a critical component of the body's anticoagulation system, playing a pivotal role in regulating blood clot formation. It is a glycoprotein that circulates in the bloodstream and acts as a cofactor for protein C, another important anticoagulant protein. The primary function of protein S is to enhance the activity of activated protein C (APC) in breaking down coagulation factors Va and VIIIa, thus inhibiting the formation of excessive blood clots.

The 24-hour urine protein test measures the amount of protein excreted in urine over a 24-hour period. This can help detect kidney disease or other conditions that affect kidney function. The normal range for this test is less than 150 milligrams per day. Factors that can affect the results include dehydration, recent contrast material for an x-ray, vaginal fluids in urine, severe stress, strenuous exercise, and urinary tract infections

The "Protein, Total, 24 HR Urine" marker in this panel is a critical measure for evaluating kidney function and detecting kidney disorders. It quantifies the total amount of protein excreted in urine over a 24-hour period. Normally, healthy kidneys filter blood and retain most proteins, preventing significant protein loss in urine. Therefore, an elevated total protein level in a 24-hour urine collection can be a sign of proteinuria, indicating kidney damage or disease. Conditions such as glomerulonephritis, diabetic nephropathy, or hypertension-related kidney damage can lead to increased urinary protein excretion. This marker is essential for diagnosing and monitoring these conditions, providing insights into the severity of kidney impairment and the effectiveness of treatment strategies. Accurate 24-hour urine collection is crucial for this measurement, as it reflects the total protein excretion more reliably than a single or random urine sample.

Total protein in random urine samples is often used in conjunction with other tests and clinical assessments to diagnose and monitor kidney diseases, such as glomerulonephritis, nephrotic syndrome, or diabetic nephropathy.

A urine protein dipstick test checks if protein is leaking into the urine, which can be an early sign of kidney disease, especially in people with high blood pressure, diabetes, or abnormal kidney blood tests (creatinine, eGFR). Results are reported as Negative (normal), Trace (very small amount, often temporary), or graded 1+ to 4+ (increasing protein, more concerning). Temporary positives may occur with strenuous exercise, fever, dehydration, UTIs, or during pregnancy. If protein is found, your healthcare provider may repeat the test with a first-morning sample and order more precise measurements (uACR or UPCR), along with related kidney and blood pressure evaluations. Staying hydrated, controlling blood pressure and blood sugar, and avoiding heavy workouts before testing can improve accuracy and kidney health.

A Protein/Creatinine Ratio (PCR), also known as the Urine Protein Creatinine Ratio (UPCR) test, measures the levels of protein and creatinine in urine. This ratio helps evaluate kidney function and detect conditions like kidney disease or proteinuria (excess protein in the urine).

The UPCR test is valuable in diagnosing and monitoring kidney-related issues, including chronic kidney disease, diabetic nephropathy, and hypertensive nephropathy. Additionally, it can help healthcare providers determine the effectiveness of treatment plans for these conditions.

The spot (random) urine protein to creatinine ratio (P/C ratio) is an alternative, fast and simple method of detecting and estimating the quantitative assessment of proteinuria.

The Protein/Creatinine Ratio in a test panel that includes Total Protein and Protein Electrophoresis, 24 Hour Urine, is a significant indicator of kidney function and health. This ratio compares the amount of protein to the amount of creatinine in a urine sample, providing a more accurate assessment of protein excretion than measuring protein alone. In healthy kidneys, protein is retained in the bloodstream, and only small amounts are excreted in urine, whereas creatinine, a waste product, is consistently excreted. An elevated Protein/Creatinine Ratio can indicate abnormal protein loss through the kidneys, a condition known as proteinuria, which is often a sign of kidney damage or disease. By normalizing the protein level to the creatinine level, this ratio helps account for variations in urine concentration and provides a more reliable assessment of proteinuria, particularly important for early detection and monitoring of kidney disease.

Autoantibodies to proteinase-3 (PR-3) are accepted as characteristic for granulomatosis with polyangiitis (GPA, Wegener's), and are detectable in 95% of the histologically proven cases. The cytoplasmic IFA pattern, (c-ANCA), is based largely on autoantibody to PR-3 which serves as the primary antigen. These autoantibodies are present in active disease.

Proteobacteria (phylum)

Proteobacteria include a wide variety of pathogens, including species within the Escherichia, Shigella Salmonella, Vibrio, and Helicobacter genera. The phylum includes a number of species that are permanent residents of the microbiota and capable of inducing nonspecific inflammation and diarrhea when their presence is increased. Proteobacteria make up approximately 2% of the gut microbiota in healthy adults.

A high-fat diet is positively associated with an abundance of Proteobacteria. Slightly increased abundance of Proteobacteria may be associated with low-grade inflammation. Proteobacteria are increased in inflammatory bowel disease and irritable bowel syndrome. Higher abundance of Proteobacteria has been associated with a moderate to severe disease course in newly discovered ulcerative colitis patients. They are associated with diarrhea in IBS.