468 CLINICAL NOTES Hypothyroidism: Its Incidence and Prevalence in Adults Older Than 55 Years of Age in an Acute Rehabilitation Unit Adrian Cristian, MD, Andrew Berlow, MD, Tharakaram Ravishankar, MD, Barry Root, MD ABSTRACT. Cristian A, Berlow A, Ravishankar T, Root B. Hypothyroidism: its incidence and prevalence in adults older than 5.5 years of age in an acute rehabilitation unit. Arch Phys Med Rehabil 1999;80:468-9. Objective: To investigate the incidence and prevalence of hypothyroidism in the acute rehabilitation unit. Design: Retrospective chart review. Setting: Inpatient rehabilitation unit. Patients: Thirty-five men and 91 women older than the age of 55 years (average, 74 years) separated into postsurgical (PS) and nonsurgical (NS) groups. Twenty-two men and 76 women were PS, 21 of whom had a history of hypothyroidism. Thirteen men and 15 women were NS, and 4 in this group had a history of hypothyroidism. Main Outcome Measures: Levels of thyroid-stimulating hormone and free thyroxine. Results: There were 34 cases of hypothyroidism, a preva- lence rate of 27%. The incidence of newly diagnosed caseswas 9% (9 of 101). Six of the newly diagnosed cases were PS patients and three were NS patients. Eleven cases of under- treated hypothyroidism were found, in 9 PS patients and 2 NS patients. The rate of undertreated hypothyroidism in the PS population was 43% (9 of 21); in the nonsurgical population, it was 50% (2 of 4). The overall rate of undertreated hypothyroid- ism for both PS and NS groups was 44% (11 of 25). Conclusion: There is a high prevalence of hypothyroidism on an inpatient rehabilitation unit and a high rate of under- treated hypothyroidism in PS patients. Screening high-risk patients is recommended. 0 1999 by the American Congress of Rehabilitation Medi- cine and the American Academy of Physical Medicine and Rehabilitation H YPOTHYROIDISM is a common disease. The prevalence rate has been studied extensively in a variety of communi- ties and has ranged from 4% to 11.6%.lm6 Hypothyroidism can be associated with significant medical problems such as de- creased myocardial contractility, decreased left ventricle ejec- tion fraction, decreased cardiac output, angina pectoris, brady- cardia, and congestive heart failure.7-10 Lipid profile abnormalities have also been reported.” This, in turn, can affect a patient’s level of function in several settings, including rehabilitation units. This study evaluated the incidence and prevalence of hypothyroidism in the acute inpatient rehabilita- tion setting. From the Division of Physical Medicine and Rehabilitation, North Shore University Hospital at Glen Cove, NY. Submitted for publication June 22, 1998. Accepted in revised form October 18, 1998. No commercial party having a direct financial interest in the results of the research supporting this article has or will confer a benefit upon the authors or upon any organization with which the authors are associated. Reprints will not be available. 0 1999 by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation 0003-9993/99/8004-5082$3.00/O Arch Phys Med Rehabil Vol 80, April 1999 Symptoms characteristic of this condition include dry skin, brittle hair, cold intolerance, paraesthesias, deafness, puffy face, constipation, muscle cramps, cognitive changes, psychosis, pleural and pericardial effusions, and carpal tunnel syndrome. These symptoms are frequently absent in the elderly, who comprise the majority of patients admitted to rehabilitation units. If they are noted by rehabilitation staff, further diagnostic testing is indicated.12 Populations at greatest risk of developing hypothyroidism include women older than 60 years of age, patients with a history of radiation to the neck, head, or chest, persons with diabetes, and patients with pernicious anemia.13Certain medica- tions, such as lithium, amiodarone, and glucocorticoids, can also lead to thyroid abnormalities.12 Postsurgicalhypothyroid patients can present with hyponatre- mia, a blunted febrile response secondary to hypothermia, congestive heart failure, and gastrointestinal or neuropsychiat- ric problems. I4 Since this population is commonly admitted to the rehabilitation unit, often with significant comorbidities, their condition may be aggravated by undetected or under- treated hypothyroidism. MATERIALS AND METHODS Men and women older than 55 years of age admitted to an inpatient rehabilitation unit were included in this retrospective study. Patients younger than the age of 55 and patients with a diagnosis of “sick euthyroid syndrome” (low to normal level of thyroid-stimulating hormone [TSH], low level of thyroxine [Td] ) were excluded. One hundred twenty-six patients (35 men and 91 women with a mean age of 74yrs) met the above criteria. Baseline TSH and free T4 levels were obtained as part of their admission screen. Testing was done between 1 and 4 weeks postevent, because this was the time frame for admission to the unit. The patients were ambulatory and able to participate in a rehabilita- tion program. The diagnosis of a new case of hypothyroidism was based on an admission TSH level of >7.5U/mL. This was an arbitrary cutoff, however, comparable values have been used previ- 0us1y.‘~Previous diagnoses of hypothyroidism were reported by patients or this information was obtained from medical records. Patients with a previous diagnosis of hypothyroidism were being treated with levothyroxine. Undertreated hypothy- roidism was defined as a baseline TSH level of >5.5U/mL while the patient was on levothyroxine. This was also an arbitrary cutoff. There were 98 postsurgery patients (22 men and 76 women). Types of surgery included coronary artery bypass graft, mitral or aortic valve replacement, open reduction internal fixation, total knee and total hip replacement, and amputation of the lower extremities. The other 28 patients (13 men and 15 women) were admitted with nonsurgical diagnoses (ie, stroke, deconditioning). Twenty-five patients had a history of hypothy- roidism. The thyroid function tests were performed using an ES 300 I Immunoassay System.a Normal values used were: TSH, .23 to 5.5mU/L; and free T4, 0.7 to 2.0ng/dL. These values are