Calcium, phosphate and uric acid: bone minerals and gout risk

The Complete panel includes three markers that often get grouped together: calcium, phosphate and uric acid. The first two are the main minerals in bone. The third is a waste product that can form crystals in joints. All three are read against the lab's printed range, and each has its own story.

Calcium: tightly controlled

About 99% of your body's calcium is in your bones and teeth. The small amount in your blood is vital for nerves, muscles and the heart, so the body holds it within a narrow band. Parathyroid hormone, from four small glands in the neck, and vitamin D do most of that work, moving calcium in and out of bone, the gut and the kidneys.

This control is so tight that blood calcium stays normal even when bones are thinning. A normal calcium does not mean your bones are strong. Bone density is measured with a scan, not a blood test.

When calcium is high or low

A mildly high calcium in a well person is most often due to an overactive parathyroid gland, a common and usually treatable condition. Other causes include too much vitamin D from supplements, dehydration, some medicines and, less commonly, cancer. A raised calcium should be repeated and followed up with a parathyroid hormone test arranged by a doctor.

A low calcium is often due to low albumin, low vitamin D or low magnesium. It can also follow neck surgery or occur with kidney disease. Very high or very low calcium can affect the heart and nerves, and LifePrint flags these results as urgent.

Phosphate: calcium's partner

Phosphate works with calcium to build bone and is also essential for energy inside every cell. The kidneys set the level by deciding how much to keep and how much to pass in urine.

• A high phosphate is most often linked to reduced kidney function. A sample that has been damaged in transit can also read falsely high.
• A low phosphate can occur with poor nutrition, heavy alcohol use, vitamin D deficiency, an overactive parathyroid gland and some medicines.
• Phosphate varies with meals and time of day, so a mildly abnormal result is often worth repeating.

Uric acid and gout

Uric acid is made when the body breaks down purines, substances found in your own cells and in foods such as red meat, organ meat and shellfish. The kidneys clear most of it. When the level stays high, uric acid can form needle-like crystals in joints, which cause the sudden, severe pain and swelling of gout, often in the big toe. It can also form kidney stones.

LifePrint uses the lab's range for uric acid and also shows the American College of Rheumatology 2020 gout guideline target. For people being treated for gout, that guideline aims to keep uric acid below 0.36 mmol/L, because crystals dissolve below this level. Your report marks results above it.

What raises uric acid

• Reduced kidney function.
• Alcohol, especially beer and spirits.
• Sugary drinks and fruit juice high in fructose.
• Excess body weight and insulin resistance, which often travel together with high uric acid.
• Some medicines, particularly water tablets.
• Dehydration and very low calorie diets.
• Family history. Genes play a large part.

A high result without symptoms

Many people have a raised uric acid and never develop gout. The ACR 2020 guideline advises against starting uric acid lowering medicine in people who have never had gout or kidney stones. A high result is still useful, because it often points to insulin resistance, kidney changes or lifestyle factors worth addressing, and it is worth knowing if joint pain ever develops.

Uric acid can fall during a gout attack, so a normal level does not rule gout out if you have had typical symptoms. A doctor can confirm the diagnosis.

If any of these markers are flagged, discuss them with a registered healthcare practitioner. Your LifePrint report explains each result and how urgently to follow up.