Hypothyroidism

First in a series of Medical Podcasts created by two Doctors for Doctors.  We aim to give a comprehensive overview of each topic.  Content includes Definition, Aetiology, Epidemiology, Anatomy if relevant, Pathology, Clinical Presentation and Features, Treatment and Prognosis.  

 

Introduction Wash hands, check right patient, introduce yourself, get permission Ask the patient to sit up straight in a chair, and expose their neck down to the shoulders. You could ask them to look up a little bit. Remove any jewellery.   InspectionInspect the hands Hypothyroidism Lethargic, disinterested Bradycardia (radial pulse)  

Introduction Wash hands, check right patient, introduce yourself, get permission Ask the patient to sit up straight in a chair, and expose their neck down to the shoulders. You could ask them to look up a little bit. Remove any jewellery.   InspectionInspect the hands Hypothyroidism Lethargic, disinterested Bradycardia (radial pulse)  

In prospective studies, the prevalence of undiagnosed subclinical hypothyroidism in pregnant women ranges from 3% to 15%. Subclinical hypothyroidism is associated with multiple adverse outcomes in the mother and fetus, including spontaneous abortion, pre-eclampsia, gestational hypertension, gestational diabetes, preterm delivery, and decreased IQ in the offspring. Only two prospective studies have evaluated the impact of levothyroxine therapy in pregnant women with subclinical hypothyroidism, and the results were mixed. Subclinical hypothyroidism is defined as raised thyrotropin combined with a normal serum free thyroxine level. The normal range of thyrotropin varies according to geographic region and ethnic background. In the absence of local normative data, the recommended upper limit of thyrotropin in the first trimester of pregnancy is 2.5 mIU/L, and 3.0 mIU/L in the second and third trimester. The thyroid gland needs to produce 50% more thyroid hormone during pregnancy to maintain a euthyroid state. Consequently, most women on levothyroxine therapy before pregnancy require an increase in dose when pregnant to maintain euthyroidism. Ongoing prospective trials that are evaluating the impact of levothyroxine therapy on adverse outcomes in the mother and fetus in women with subclinical hypothyroidism will provide crucial data on the role of thyroid hormone replacement in pregnancy.  

Includes a demonstration of the standard thyroid exam, review of the etiologies of goiters, and an overview of the many physical findings of hypothyroidism a...  

Includes a demonstration of the standard thyroid exam, review of the etiologies of goiters, and an overview of the many physical findings of hypothyroidism a...  

A 67 year old white woman presented to her family doctor in January 2013 with a small asymptomatic thyroid swelling. Her serum thyroid stimulating hormone (TSH) concentration was high (37 mIU/L; reference range 0.5-4.5) and serum free thyroxine was low (5.4 pmol/L; 10-21), consistent with a hypothyroid state. However, she had no clinical features of hypothyroidism. Ultrasonography of the neck showed diffuse hypoechoic enlargement of the thyroid gland, with no retrosternal extension. Her serum anti-thyroid peroxidase (anti-TPO) value was also high (>600 kU/L; <35 kU/L). These features were suggestive of autoimmune (Hashimoto’s) thyroiditis. She was advised to take thyroxine tablets (100 µg) daily, and after two months her neck swelling reduced in size and her serum TSH concentration normalised (1.2 mU/L).  

A 92 year old woman presented to the emergency department after collapsing at home. She recalled standing from her chair, feeling lightheaded, and then collapsing. She had felt generally weak for more than a year, with weight loss of 56 lb (25.2 kg) but no change in bowel habit, dysphagia, or gastrointestinal bleeding. Her medical history included hypertension, hypothyroidism, and anaemia (which was currently being investigated by her general practitioner). Among other drugs, she was taking lisinopril, bendroflumethiazide, and levothyroxine. Her son had died at 60 years of age from large bowel obstruction and perforation secondary to colon cancer.  

I was just wondering how hypothyroidism causes hyperprolactinaemia? I thought that TRH stimulates prolactin, so if TRH is low surely prolactin should be low too?  

How dose hypothyroidism cause hyperprolactinemia ?  

A 67 year old white woman presented to her family doctor in January 2013 with a small asymptomatic thyroid swelling. Her serum thyroid stimulating hormone (TSH) concentration was high (37 mIU/L; reference range 0.5-4.5) and serum free thyroxine was low (5.4 pmol/L; 10-21), consistent with a hypothyroid state. However, she had no clinical features of hypothyroidism. Ultrasonography of the neck showed diffuse hypoechoic enlargement of the thyroid gland, with no retrosternal extension. Her serum anti-thyroid peroxidase (anti-TPO) value was also high (>600 kU/L; <35 kU/L). These features were suggestive of autoimmune (Hashimoto’s) thyroiditis. She was advised to take thyroxine tablets (100 µg) daily, and after two months her neck swelling reduced in size and her serum TSH concentration normalised (1.2 mU/L).  

A 92 year old woman presented to the emergency department after collapsing at home. She recalled standing from her chair, feeling lightheaded, and then collapsing. She had felt generally weak for more than a year, with weight loss of 56 lb (25.2 kg) but no change in bowel habit, dysphagia, or gastrointestinal bleeding. Her medical history included hypertension, hypothyroidism, and anaemia (which was currently being investigated by her general practitioner). Among other drugs, she was taking lisinopril, bendroflumethiazide, and levothyroxine. Her son had died at 60 years of age from large bowel obstruction and perforation secondary to colon cancer.  

Results suggest why standard treatments fail some patients and how to help themAn international research team led by physician-scientists at Rush University Medical...  

54 yo F with no PMHx, but admittedly has not been seen by an MD in many years, presents after her daughter visited from our-of-town and found her slightly confused. The patient is disoriented, but able to provide some history. She describes progressive fatigue over several weeks. Vitals signs are remarkable for hypothermia 94F, HR 52, BP 150/90, RR 12, SpO2 100%RA. Exam is notable for AAO2, no focal neuro deficits, prominent facial swelling, and non-pitting lower extremity edema. FS glucose 160. Laboratory analysis is concerning for mild hyponatremia and severe hypothyroidism.  

A 56 year old woman with hypothyroidism after total thyroidectomy presented to the emergency department after an episode of near syncope. When she arrived she had hypotension and atrial fibrillation, with a rapid ventricular response. She reported a history of progressive weakness, weight loss, polyuria, polydipsia, anorexia, and fatigue. Urine analysis was positive for leucocyte esterase and pyuria. She was admitted to the intensive care unit with a diagnosis of severe sepsis of urinary source and atrial fibrillation with a rapid ventricular response. After aggressive fluid resuscitation and the administration of intravenous antibiotics, her heart spontaneously converted to a normal rhythm and she appeared well perfused but remained hypotensive. Review of her medical record showed that her therapeutic thyroxine replacement had recently been decreased because of low thyrotrophin. On perusal of her records from an another facility it was noted that she had undergone pituitary mass resection and irradiation 20 years earlier.  

A 56 year old woman with hypothyroidism after total thyroidectomy presented to the emergency department after an episode of near syncope. When she arrived she had hypotension and atrial fibrillation, with a rapid ventricular response. She reported a history of progressive weakness, weight loss, polyuria, polydipsia, anorexia, and fatigue. Urine analysis was positive for leucocyte esterase and pyuria. She was admitted to the intensive care unit with a diagnosis of severe sepsis of urinary source and atrial fibrillation with a rapid ventricular response. After aggressive fluid resuscitation and the administration of intravenous antibiotics, her heart spontaneously converted to a normal rhythm and she appeared well perfused but remained hypotensive. Review of her medical record showed that her therapeutic thyroxine replacement had recently been decreased because of low thyrotrophin. On perusal of her records from an another facility it was noted that she had undergone pituitary mass resection and irradiation 20 years earlier.  

Case Presentation 57 yr old M with a history of CAD, hypothyroidism and HTN presents to the emergency department with palpitations. He reports that the  

A 29 year old right hand dominant chef presented to the emergency department with a four day history of feeling “not normal.” He was sent home from work because of a gradual onset of dull pain on the left side of his neck radiating up into his head, which was getting progressively worse, as well as “seeing two of everything.” The pain was not influenced by changes in posture. In addition, his right side felt numb and he was dropping things at work. He felt unsteady on his feet, which prompted him to seek medical advice. He thought all his symptoms had come on suddenly and were gradually getting worse. He denied any recent alcohol consumption, illicit drug use, seizure activity, head injury, or loss of consciousness. He had no medical history of note, apart from hypothyroidism, for which he was taking thyroxine.  

Dr. Sathya Krishnasamy presents cases to illuminate the physiology of thyroid disease including hypothyroidism, hyperthyroidism and thyroid nodules. Some ite...