There is evidence that the prevalence of diabetes mellitus, hypothyroidism, and rheumatoid arthritis is higher in people with carpal tunnel syndrome, but there is insufficient evidence to recommend routine laboratory screening for concurrent disease in people with a new diagnosis of carpal tunnel syndrome.

• A systematic review aimed to investigate whether there was an increased prevalence of specific conditions in people with carpal tunnel syndrome (CTS) and whether this evidence would support laboratory screening for these conditions [van Dijk et al, 2003].
• Medline, Embase, and the Cochrane Controlled Trial Register were searched for key words related to CTS and associated diseases.
• After an initial search, the authors limited their search to diabetes mellitus, hypothyroidism, and rheumatoid arthritis and identified nine articles, with a total of 4908 people with CTS and 7671 controls, that met the selection criteria.
• The prevalence of concurrent diseases was higher in people with CTS than in controls: for diabetes mellitus (pooled odds ratios 2.2, 95% CI 1.5 to 3.1), for hypothyroidism (pooled OR 1.4, 95% CI 1.0 to 2.0), and for rheumatoid arthritis (pooled OR 2.2, 95% CI 1.4 to 3.4).
• Only one study [Atcheson et al, 1998] specifically addressed the issue of whether the concurrent condition had been diagnosed at the time of presentation. New diagnoses of concurrent disease at the time of diagnosis were as follows:
• Diabetes mellitus: 17 people had diabetes mellitus but only one diagnosis was new.
• Hypothyroidism: 18 people had hypothyroidism and three diagnoses were new.
• Rheumatoid arthritis: all five diagnoses were new.
• The authors concluded that there was insufficient evidence to recommend routine laboratory screening for concurrent disease in all people newly diagnosed with CTS.