Dehydration may cause a rise in the plasma levels of routine chemistries including calcium, protein, amylase, lactate dehydrogenase, transaminases, and creatinine kinase. Underlying disease states associated with these levels need to be excluded, however. Patients present with prerenal azotemia, and the initial BUN to creatinine ratio may exceed 30:1. Leukocytosis is often present secondary to stress, demarginalization, and hemoconcentration [7]. Infection, however, should be ruled out as the cause of any marked elevation in white blood cell count. Hemoglobin and hemat ocrit concen- trations may be elevated falsely because of hemoconcentration, and anemia should be suspected in a patient with a normal hematocrit on examination [20]. A mild high anion gap metabolic acidosis, characterized by an arterial pH above 7.3 and bicarbonate level greater than 15 is common in HHS [22,33]. This acidosis can be multifactorial, contributed to by dehydration, renal failure, starvation, or mild lactic acidosis. Vomiting or the use of thiazide diuretics can cause a metabolic alkalosis that can mask the degree of acidosis [4,12,22]. If acidosis is severe, lactic acidosis caused by hypovolemia and decreased perfusion, underlying infection, or other concurrent severe illness (eg, ischemic bowel) should be considered [4]. Arterial blood gas measure- ments can help clarify what is sometimes a complicated mixed acid base picture, and indicate other cardiac or pulmonary comorbidities. Although HHS is de scribed as a nonketotic hyperosmolar state, there is often some elevation of serum ketones, including b-hydroxybutyrate, which are related mostly to the starvation ketosis or to dehydration [2,19]. Urinalysis always is indicated and may demo nstrate some degree of ketonuria also. Gross proteinuria suggests the presence of underlying renal disease. Other studies Other diagnostic studies are obtained routinely in the ED evaluation to look for precipitating or underlying illnesses. The initial chest radiograph may be falsely negative for pneumonitis in light of the state of dehydration, and cardiomegaly in this setting suggests likely cardiomyopathy [19].An electrocardiogram always is indicated to look for signs of ischemia and infarction, and acute changes related to electrolyte deficiencies. CT of the brain to exclude intracranial pathology is indicated because of the frequent presence of altered cognition. Lumbar puncture and toxicologic studies should be performed if indicated. Emergency department management Management in the ED begins with a rapid clinical assessment focused on the elements of history and physical, and with appropriate evaluation and monitoring of respiratory, cardiovascular, and central nervous system function. The diagnosis of the extreme decompensated diabetic state can be 639HYPEROSMOLAR HYPERGLYCEMIC STATE Hypothyroidism: Mimicker of Common Complaints Matthew C. Tews, DO a , Sid M. Shah, MD, FACEP b, * , Ved V. Gossain, MD, FACP, FACEP c a College of Osteopathic Medicine, Emergency Medicine Residency Program, Michigan State University–Lansing, P.O. Box 30480, Lansing, MI 48909, USA b Michigan State University, Attending Physician Emergency Medicine, Ingham Regional Medical, Center 401 W. Greenlawn Avenue, Lansing, MI 48910, USA c Division of Endocrinology, Department of Medicine, Michigan State University, Lansing, MI 48909, USA Patients with hypothyroidism may present with vague symptoms such as fatigue, arthralgias, myalgias, muscle cramps, headaches, and ‘‘not feeling well.’’ These are also among the more common complaints encountered by the emergency physicians. The disease spectrum of hypothyroidism ranges from an asymptomatic, subclin ical condition to the rare, life-threaten ing myxedema coma, and thus can be a challenging diagnosis to make. A progressive and chronic disease, hypothyroidism results from diminished thyroid hormone production. It slows metabolic functions in every organ system in the body. Commonly, clinical presentation of hypothyroidism can be confused with effects of aging in the elderl y, musculoskeletal or a psychiatric illness such as depression in the younger patients. Spontaneously occurring hypothyroidism is relatively common, with prevalence between 1% to 2%, and is 10 times more common in women than in men [1]. The probability of developing spontaneous hypothyroidism increases with age, with women having a mean age at diagnosis of around 60 years [2]. A recent survey showed that 9.5% out of nearly 26,000 visitors to a statewide health fair in Colorado had elevated circulating thyroid stimulating hormone (TSH) levels, indicating underlying hypothyroidism [3]. One large study performed in England found the prevalence of hypothyroidism to be around 18/100 0 women and less than 1/1000 men in the general population studied [4]. The study also revealed a higher * Corresponding author. E-mail address: sidshah@comcast.net (S.M. Shah). 0733-8627/05/$ - see front matter Ó 2005 Elsevier Inc. All rights reserved. doi:10.1016/j.emc.2005.03.013 emed.theclinics.com Emerg Med Clin N Am 23 (2005) 649–667 Hyperthyroidism Nathanael J. McKeown, DO a , Matthew C. Tews, DO a , Ved V. Gossain, MD, FACP, FACEP b , Sid M. Shah, MD, FACEP c, * a College of Osteopathic Medicine, Emergency Medicine Residency Program, Michigan State University, PO Box 30480, Lansing, MI 48909, USA b Division of Endocrinology, Department of Medicine, B234 Clinical Center, 138 Service Road, Michigan State University, Lansing, MI 48824, USA c Michigan State University, Emergency Medicine, Ingham Regional Medical Center, 401 West Greenlawn, Lansing, MI 48910, USA Hyperthyroidism is a hypermetabolic state that results from excess synthesis and release of thyroid hormone from the thyroid gland. Thyrotoxicosis is a general term referring to all causes of excess thyroid hormone in the body, including exogenous intake of thyroid hormone preparations. Although the terms hyperthyroidism and thyrotoxicosis are by definition not the same, they often are used interchangeably [1]. The clinical spectrum of hyperthyroidism varies from asymptomatic, subclinical hyperthyroidism to the life-threatening thyroid storm. Sub- clinical hyperthyroidism is diagnosed in asymptomatic patients on the basis of abnormal laboratory tests (low thyrotropin [TSH] but normal free T4 and free T3), and is probably more common than generally believed. Overt clinical hyperthyroidism presents with typical signs and symptoms. Thyroid storm is the severe life-threatening form of hyperthyroidism. It usually is brought about by a precipitating event in patients with undiagnosed or undertreated hyperthyroidism. Epidemiology and pathophysiology The overall incidence of subclinical and overt hyperthyroidism has been estimated to be 0.05 to 0.1% in the general population [2]. It occurs at all ages, but it is more common in women than in men. In a recent US study * Corresponding author. E-mail address: sidshah@comcast.net (S.M. Shah). 0733-8627/05/$ - see front matter Ó 2005 Elsevier Inc. All rights reserved. doi:10.1016/j.emc.2005.03.002 emed.theclinics.com Emerg Med Clin N Am 23 (2005) 669–685 . Corresponding author. E-mail address: sidshah@comcast.net (S.M. Shah). 073 3-8 627 /05/$ - see front matter Ó 20 05 Elsevier Inc. All rights reserved. doi:10.1016/j.emc .20 05.03.0 02 emed.theclinics.com Emerg. higher * Corresponding author. E-mail address: sidshah@comcast.net (S.M. Shah). 073 3-8 627 /05/$ - see front matter Ó 20 05 Elsevier Inc. All rights reserved. doi:10.1016/j.emc .20 05.03.013 emed.theclinics.com Emerg. life-threaten ing myxedema coma, and thus can be a challenging diagnosis to make. A progressive and chronic disease, hypothyroidism results from diminished thyroid hormone production. It slows metabolic