The rubidium (Rb) urine test measures the amount of rubidium excreted in the urine. Rubidium is a trace element in the human body, and its role is not entirely understood. Still, it is thought to be involved in various physiological processes, including ion transport and enzyme activation. Rubidium is widespread in plants, animals, and almost all biological systems. Physiologically, rubidium most resembles potassium and can be actively taken up and treated by animal cells.
This test might be ordered for several reasons:
- Nutritional assessment: To evaluate rubidium levels as part of a comprehensive nutritional analysis.
- Toxicity assessment: In cases of suspected heavy metal exposure or poisoning, though rubidium toxicity is rare.
- Research purposes: To study rubidium metabolism or its physiological and pathological roles in the body.
Factors Affecting Results
- Diet: Foods like coffee, tea, and certain fruits can influence rubidium levels.
- Medications and supplements: Some drugs and dietary supplements might alter rubidium excretion.
- Hydration status: Dehydration or overhydration can affect urine concentration and, thereby, rubidium measurements.
Clinical Relevance
Although rubidium is not a commonly measured element in clinical practice, understanding its excretion can provide insights into various metabolic and nutritional states. However, since rubidium's role in the human body is not fully understood, the clinical interpretation of abnormal rubidium levels should be approached cautiously and in context with other clinical findings.
- Low levels: This may indicate inadequate dietary intake of rubidium or issues with absorption.
- High levels: This could suggest excessive dietary intake or exposure to rubidium, although high levels without toxicity are generally not harmful.
Determination of metals is done by ICP-MS (Inductively Coupled Plasma Mass Spectrometry, Inductively Coupled Argon Plasma Mass Spectrometry), a method that enables the simultaneous detection of many metals. Its sensitivity and accuracy are significantly better than conventional atomic absorption, with the ability to measure metals at concentrations up to 1 in 1015 (1 in 1 quadrillion, ppq)!
