Autoimmune rheumatic diseases are conditions in which the immune system attacks the joints and certain systems. They are often difficult to diagnose, as their symptoms can be vague, vary from patient to patient, and often overlap. Laboratory testing can provide useful information, but no single test provides a definitive diagnosis for any one rheumatic disease. Diagnosis is most often based on a compilation of symptoms and signs, including clinical information and laboratory test results.

Testing for antinuclear antibodies (ANAs) using an immunofluorescence assay (IFA) is a good first approach for laboratory evaluation of patients suspected of having certain autoimmune rheumatic diseases. ANAs, a group of autoantibodies directed against diverse nuclear and cytoplasmic antigens, are associated with several autoimmune rheumatic diseases.

These include:

- systemic lupus erythematosus (SLE),

- systemic sclerosis (SSc),

- and mixed connective tissue disease (MCTD).

An antiparietal cell antibody test is a blood test that looks for antibodies against the parietal cells of the stomach. The parietal cells make and release a substance that the body needs to absorb vitamin B12.

This test is used as an aid in the diagnosis of certain autoimmune thrombotic disorders, such as antiphospholipid syndrome (aPS). Antibodies to PS/PT correlate with the presence of lupus anticoagulants (LA) and this test may be useful in cases with difficult LA test interpretation. This assay may also assist in the determination of risk for thrombosis as well as obstetric complications in patients with antiphospholipid antibodies.

This test is used as an aid in the diagnosis of certain autoimmune thrombotic disorders, such as antiphospholipid syndrome (aPS). Antibodies to PS/PT correlate with the presence of lupus anticoagulants (LA) and this test may be useful in cases with difficult LA test interpretation. This assay may also assist in the determination of risk for thrombosis as well as obstetric complications in patients with antiphospholipid antibodies.

This test is used as an aid in the diagnosis of certain autoimmune thrombotic disorders, such as antiphospholipid syndrome (aPS). Antibodies to PS/PT correlate with the presence of lupus anticoagulants (LA) and this test may be useful in cases with difficult LA test interpretation. This assay may also assist in the determination of risk for thrombosis as well as obstetric complications in patients with antiphospholipid antibodies.

For diagnosis and monitoring inflammatory activity in primary systemic small vessel vasculitides. Antineutrophil antibodies are best demonstrated in these diseases by using a combination of IFA and EIAs that detect ANCA specific for PR3-ANCA or MPO-ANCA. Presence of anti-MPO antibodies are highly specific for idiopathic and vasculitis associated crescentic glomerulonephritis, classic polyarteritis nodosa, Churg-Strauss syndrome, and polyangiitis overlap syndrome without renal involvement.

Scl-70 antibody is seen in 20% of people with scleroderma (also known as systemic sclerosis), and in some people with CREST syndrome (calcinosis, Raynaud, esophageal dysfunction, sclerodactyly, telangiectasia).

The ASO test is primarily used to help determine whether a recent strep infection with group A Streptococcus:

Studies have shown that the ratio of apolipoprotein A-1:apolipoprotein B may correlate better with increased risk of coronary artery disease (CAD) than total cholesterol, and LDL:HDL ratio.

ApoA-I, or Apolipoprotein A-I, plays a crucial role in understanding heart health and managing potential risks related to cardiovascular diseases. ApoA-I is the main protein component of high-density lipoprotein (HDL) in the blood. HDL is often referred to as "good cholesterol" because it helps transport cholesterol from the arteries to the liver, where it can be processed and removed from the body. This process is essential for maintaining healthy artery walls and preventing the build-up of plaques that can lead to heart attacks and strokes. Higher levels of ApoA-I and consequently HDL are generally associated with a lower risk of heart disease. The measurement of ApoA-I in a lipid panel provides valuable information about a person's HDL levels and overall cardiovascular health. By assessing ApoA-I, healthcare providers can better understand an individual's risk for heart disease and tailor treatment plans to improve heart health, such as recommending lifestyle changes or prescribing medication to manage cholesterol levels effectively. 

Apolipoprotein A is a protein carried in HDL ("good") cholesterol. It helps start the process for HDL to remove bad types of cholesterol from your body. In this way, apolipoprotein A can help to lower your risk for cardiovascular disease. Apolipoprotein A levels can be measured. But it's more common to measure the HDL and LDL ("bad") cholesterol when looking at cardiovascular risk.

This biomarker is useful for:

- Evaluating risk for atherosclerotic cardiovascular disease

- Aiding in the detection of Tangier disease

Apolipoprotein A is a protein carried in HDL ("good") cholesterol. It helps start the process for HDL to remove bad types of cholesterol from your body. In this way, apolipoprotein A can help to lower your risk for cardiovascular disease. Apolipoprotein A levels can be measured. But it's more common to measure the HDL and LDL ("bad") cholesterol when looking at cardiovascular risk.

This biomarker is useful for:

- Evaluating risk for atherosclerotic cardiovascular disease

- Aiding in the detection of Tangier disease

- Apolipoprotein B (apoB) levels are used to evaluate the risk for cardiovascular disease. 
- LDL and its major protein, apolipoprotein B, play an essential role in lipid transport and metabolism. 
- ApoB levels are higher in males than in females and tend to increase with age.
- ApoB plays a central role in carrying cholesterol and triglycerides from the liver and gut to utilization and storage sites.
- Incontestable data support the concept that apoB is a better tool to assess cardiovascular disease than LDL-C and non-DHL-C.

Studies have shown that the ratio of apolipoprotein A-1:apolipoprotein B may correlate better with increased risk of coronary artery disease (CAD) than total cholesterol, and LDL:HDL ratio.

Apolipoprotein B100 (apoB100) is a building block of very low-density lipoproteins (VLDLs), intermediate-density lipoproteins (IDLs), and low-density lipoproteins (LDLs). These related molecules all transport fats and cholesterol in the bloodstream.

Cerebrospinal fluid (CSF) is a clear, watery liquid that flows around the brain and spinal cord, surrounding and protecting them. CSF testing is performed to evaluate the level or concentration of different substances and cells in CSF in order to diagnose conditions affecting the brain and spinal cord (central nervous system).

The appearance of the sample of CSF is usually compared to a sample of water.

Normal joints contain a small volume of synovial fluid that is highly viscous, clear, and essentially acellular.

Clarity: Increased opacity of the fluid is usually due to abnormally large numbers of nucleated or red blood cells (RBCs). However, translucent or even opaque fluid may be the result of acellular material. Examples include lipids in fat necrosis, chyle droplets, or innumerable monosodium urate (MSU) crystals aspirated from gouty tophi.

Semen is typically whitish-gray with a jelly-like texture, but it can fluctuate with different lifestyle changes. Unless you’re experiencing other symptoms, temporary changes in the color of your semen usually aren’t a cause for concern.

If your semen is a different color than usual, take a few moments to scan your body for other changes.

Semen that’s tinged with yellow, green, pink, red, orange, or brown isn’t ideal, but it may not be cause for concern unless it’s accompanied by other unusual symptoms.

Genital soreness, itching, or burning could point to an underlying infection or other condition. When it comes to consistency, semen that’s thicker than usual could be a sign of dehydration.