Phosphate (as Phosphorus) - Serum phosphorus (Phosphate) levels alone are of limited diagnostic value and should be correlated with serum calcium levels. An increased phosphorus with decreased calcium suggests either hypoparathyroidism or renal disease. A decreased phosphorus and an increased calcium suggests hyperparathyroidism or sarcoidosis. When both calcium and phosphorus are decreased diagnostic considerations include malabsorption, vitamin D deficiency and renal tubular acidosis. Increased phosphorus and normal or increased calcium suggests Milk-alkali syndrome or hypervitaminosis D.

Renin, also known as angiotensinogenase, is an enzyme that the kidneys produce to regulate aldosterone production. It’s also essential in the renin–angiotensin aldosterone system (RAAS) which maintains your body’s fluid balance and blood pressure. Aldosterone is the primary of several endogenous members of the class of mineralocorticoids in humans. Aldosterone tends to promote sodium and water retention, and lower plasma postasium concentrations.

This test measures the amount of dihydrotestosterone (DHT) in the blood.  Low DHT has been associated with low libido and high DHT has been linked to acne, hair loss and benign prostatic inflammation in a minority of men.

The thyroid stimulating hormone (TSH) is produced and secreted by the pituitary gland and stimulates the thyroid to produce T3 and T4. When TSH is elevated, low thyroid function may be indicated. If TSH is low it is indicative of high thyroid function. A study found that TSH was suppressed in all subjects after food, so fasting may be suggested although it is not reqired by Quest. Free T4 and Free T4 values did not change significantly after eating.

Thyroxine-binding globulin (TBG) is a globulin that binds thyroid hormones in circulation. It is one of three transport proteins (along with transthyretin and serum albumin) responsible for carrying the thyroid hormones thyroxine (T4) and triiodothyronine (T3) in the bloodstream. Of these three proteins, TBG has the highest affinity for T4 and T3 but is present in the lowest concentration. Despite its low concentration, TBG carries the majority of T4 in the blood plasma.

Iodine, Serum/Plasma - Iodine is an essential element that is required for thyroid hormone production. The measurement of iodine serves as an index of adequate dietary intake and iodine overload, particularly from iodine-containing drugs.

Patients with diabetes may get a C-peptide test as a means of distinguishing type 1 diabetes from type 2 diabetes or Maturity onset diabetes of the young (MODY). Measuring C-peptide can help to determine how much of their own natural insulin a person is producing as C-peptide is secreted in equimolar amounts to insulin. C-peptide levels are measured instead of insulin levels because C-peptide can assess a person's own insulin secretion even if they receive insulin injections, and because the liver metabolizes a large and variable amount of insulin secreted into the portal vein but does not metabolize C-peptide, meaning blood C-peptide may be a better measure of portal insulin secretion than insulin itself.

The serum iron test measures the amount of iron in your blood. The total iron-binding capacity (TIBC) test looks at how well the iron moves through your body.

The Urinalysis test panel screens for a variety of conditions including urinary tract infections ( UTI ), urinary bladder disease, kidney disease and diabetes. Tests included: Color, Appearance, Specific gravity, pH, Protein, Glucose, Occult blood, Ketones, Leukocyte esterase, Nitrite, Bilirubin, Urobilinogen, and Microscopic examination of urine sediment

A Magnesium RBC test can provide an earlier indicator of magnesium deficiency that a standard magnesium blood test. When levels are low, the body will pull magnesium from the cells to keep blood levels normal. In this case, a magnesium blood test may show normal levels while a magnesium RBC test will give a more accurate result.

The Rheumatoid Arthritis Factor is often evaluated in patients suspected of having any form of arthritis or destructive articular disease even though positive results can be due to other causes, and negative results do not rule out disease. But, in combination with signs and symptoms, it can play a role in both diagnosis and disease prognosis. It is part of the usual disease criteria of rheumatoid arthritis.