High prevalence of previously unknown subclinical hypothyroidism in obese patients referred to a sleep clinic for sleep disordered breathing.
OBJECTIVE
To evaluate the prevalence of previously unknown hypothyroidism in adult male and female patients with a wide range of body mass index (BMI) values, referred to a Sleep Clinic because of sleep disordered breathing (SDB).


RESULTS
Serum concentrations of thyroid stimulating hormone (TSH) and free thyroxin (fT4), as well as forced vital capacity (FVC), PaO2, PaCO2, the Epworth sleepiness scale (ESS), respiratory disturbance index (RDI), loud snoring, and the percentage of total sleep time (TST) with <90% oxyhemoglobin saturation (TST(saO2<90%)) were measured in 78 overweight and obese adult subjects with no previous diagnosis of hypothyroidism (age: 18-72 years). The prevalence of previously undiagnosed subclinical hypothyroidism in the population as a whole was 11.5%. BMI, TSH and ESS were significantly higher in the hypothyroid than the euthyroid subjects, but there was no significant between-group difference in RDI, TST(saO2<90%) or the other investigated variables, including the prevalence of obstructive sleep apnea (OSA). Among the hypothyroid individuals, BMI, neck circumference, ESS, RDI and TST(Sao2<90%) were significantly higher in those with than in those without OSA. Furthermore, there was a clear trend towards a lower FVC% and higher snoring score in the OSA patients.


CONCLUSIONS
Our results demonstrate a higher prevalence of hypothyroidism than that commonly reported in overweight and obese individuals referred to a Sleep Clinic for polysomnography because of SDB, thus suggesting that thyroid function should be evaluated in all obese patients suffering from SDB despite economic concerns.
Resta
O
O
Respiratory Diseases, Department of Clinical Methodology and Medical-Surgical Technologies, University of Bari, School of Medicine, Bari, Italy.
Pannacciulli
N
N
Di Gioia
G
G
Stefàno
A
A
Barbaro
M P Foschino
MP
De Pergola
G
G
D000293:Adolescent; D000328:Adult; D000368:Aged; D015992:Body Mass Index; D005260:Female; D006801:Humans; D007037:Hypothyroidism / Q000097:blood / Q000150:complications* / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000097:blood / Q000150:complications* / Q000453:epidemiology; D017286:Polysomnography; D015995:Prevalence; D012307:Risk Factors; D012891:Sleep Apnea Syndromes / Q000097:blood / Q000453:epidemiology / Q000209:etiology*; D012913:Snoring / Q000209:etiology; D013972:Thyrotropin / Q000097:blood
D013972:Thyrotropin