Rubidium

Hair rubidium is an exploratory research marker. Studies have found differences between groups, but no validated evidence shows how to use your result to guide prevention, diagnose a deficiency or monitor treatment. There is no established hair level associated with the best health outcomes.

What the Number Represents

Rubidium belongs to the same chemical family as potassium and sodium and can enter cells through some of the transport systems that handle potassium. It hasn't been established as an essential human nutrient, and its biological role remains poorly understood.

This test measures total elemental rubidium in a cut hair sample using ICP-MS. This laboratory technique detects small amounts of elements. Results are reported in micrograms per gram of hair (µg/g).

Hair can contain elements incorporated during growth and material deposited on its surface afterward. The length sampled therefore matters, but hair rubidium hasn't been validated as a precise average of your dietary intake over a particular number of months. Its concentration also cannot be translated into the amount in your blood or organs.

Multiple Sclerosis

One study compared 48 people with relapsing-remitting multiple sclerosis with 51 controls from the same region. Hair rubidium was lower in the MS group. Some people with MS fell below nearly all controls, though the results of the two groups overlapped substantially.

Levels weren't associated with disability, disease duration or age. Everyone with MS received natalizumab, so the comparison couldn't separate disease-related differences from treatment effects. The authors proposed impaired absorption as one possible explanation; they did not test it.

Findings in Athletes

A study compared 66 young male wrestlers with 92 young military cadets who had previous sports training. Wrestlers with higher hair rubidium also tended to have higher hair potassium, sodium and caesium. The relationship was strongest with potassium.

Some wrestling groups had substantially higher hair rubidium than the controls. These comparisons don't establish that training or sweating caused the differences. They also don't validate hair rubidium as a measure of electrolyte balance, recovery or athletic performance.

Findings From Other Body Fluids

Studies of rubidium in urine, whole blood and amniotic fluid concern different measurements from this hair test. They help frame research questions, but their findings cannot be used to interpret your hair concentration.

The blood-pressure and dialysis studies measured associations at one point in time. The pregnancy study followed participants from sampling to birth. All were observational, so none establishes that changing rubidium improves these outcomes.

Geographic Differences

Among children in southwest Sardinia, hair rubidium was higher on Sant'Antioco Island than around the abandoned mining sites near Iglesias. Local geology and differences in locally produced food were possible explanations. The study did not identify the source of each child's rubidium or show what would happen to an individual's result after moving.

When Results Can Be Misleading

In a 2001 investigation, portions of one person's hair sample were sent to six commercial laboratories. Reported mineral concentrations differed substantially between laboratories, and they gave conflicting interpretations and supplement advice. This was a broad hair-mineral investigation, not an estimate of the error in a current rubidium result.

Research on hair elements identifies several sources of uncertainty. Their size varies by element and preparation method:

• External material: dust, sweat, water and hair products can contribute elements to the strand, complicating estimates of what entered through your body.
• Chemical treatments: dyeing, bleaching and perming can alter hair and its elemental composition.
• Sample preparation: washing and chemical processing can affect measured concentrations. Washing does not always separate surface contamination from material incorporated during growth.
• Sampling differences: scalp location, hair length and growth rate affect the material and period represented.
• Laboratory differences: preparation procedures and calibration can produce differences even when laboratories use the same general analytical technique.