Rubidium content in autopsy liver tissue samples from Greenlandic Inuit and Danes measured by X-ray fluorescence spectrometry

Background: The biological function of rubidium (Rb) is unknown, but this alkali metal probably has a normal biologic role.

Objective: To measure the content of Rb in liver tissue samples from Greenlandic Inuit using X-ray fluorescence spectrometry, and compare the results with those obtained in liver samples from ethnic Danes.

Study design: Observational, descriptive survey on environmental pathology.

Methods: The setting was related to forensic medicine and hospitalised care in Nuuk, Ilulissat and Copenhagen. Normal liver tissue was obtained at autopsy from 50 Greenlandic Inuit (27 men) with a median age of 61 years (range 23–83) and from 42 Danes (31 men) with a median age of 38 years (range 16–83).

Results: Liver Rb content in Inuit was not significantly different compared with Danes. There was no significant gender difference in liver Rb content either in Inuit or in Danes. The content of Rb given as median (5–95 percentile) was 0.1837 mmol/kg dry liver (0.1041–0.3147) in Inuit, and 0.1965 mmol/kg dry liver (0.0799–0.2815) in Danes (p=0.6). There was an inverse correlation between liver Rb content and age in Inuit (rs=−0.45, p=0.002) but not in Danes. Median hepatic Rb index (Rb content in μmol/kg dry weight divided by age in years) in Inuit was 3.05 and in Danes 4.21 (p=0.02). The correlations between liver Rb and liver potassium content were: Inuit rs=0.28, p=0.07; Danes rs=0.25, p=0.08; combined series rs=0.34, p=0.01.

Conclusions: Inuit have liver Rb levels, which are quite similar to the levels found in Danes. In Inuit, liver Rb content appears to decrease with age.