Hypothyroidism and Hyperthyroidism in the Elderly

Chien Yung-Chang , MD .

Free T4

• Reference range 0.7-1.8 ng/Dl .

• Converted to triiodothyronine (T3) .

• The thyroid gland is the sole source of T4 .

• Free T4 measures the nonprotein-bound circulating T4 .

Total T4

• Normal range 50-120 ng/mL , 5-12 mcg/dL .• Measurement of total T4 is not particularly

helpful .• Only 0.03% of T4 circulates in the unbound

state .• There is no clinical indication for performing

total thyroid hormone measurement .

TSH

• Normal 0.4-5.5 mIU/L .

• Serum TSH will be decreased to<0.1 mIU/L in most hyperthyroid patients .

• The findings of a low serum T4 and low TSH mandate a search for pituitary disease .

T3

• T3 is more biologically active .

• Binding proteins : thyroid-binding globulin , transthyretin and albumin .

• T3 thyrotoxicoisis : approximately 5% of clinically hyperthyroid patients with a normal free T4 level .

Functional examinations

• Measure the uptake of iodine into the thyroid gland .

• The iodine isotopes : used to identify nodular thyroid disease , to determine if these nodules are hot ( functioning ) or cold ( hypofunctioning ) , to determine the cause for the hyperthyroid state ( Graves’ disease vs thyroiditis ) and to determine a dose of radioiodine for treatment .

Erythrocyte sedimentation rate

• To confirm the diagnosis of subacute ( viral ) thyroiditis in patients with tenderness on thyroid palpation .

The Role of the History in Diagnosing Hypothyroidism

• Previous thyroid ablation .

• Elevated thyroid autoantibodies .

• Thyroid surgery .

• Medicatins containing lithium or iodine .

• The most common cause of hypothyroidism is autoimmune or Hashimoto’s thyroiditis .

Signs and Symptoms of Hypothyroidism

• Less active than usual with loss of interest in things previously enjoyed .

• Lethargy , and decreased mobility .

• Fatigue .

• Dry skin .

Sings and Symptoms of Hypothyroidism (continued )

• Apathy and psychomotor retardation .

• Weakness , arthralgia , myalgia , coarsening of the voice , constipation , edema , weight gain , cold intolerance .

• Alveolar hypoventilation => CO2 retention and coma .

The Physical Examination in Hypothyroidism

• Hypotension or diastolic hypertension .

• Low body temperature and bradycardia .

• Facial features that are puffy and coarse .

• The skin : dry and cold .

• Carotenemia : An orange or yellow tint without scleral icterus .

The Physical Examination in Hypothyroidism ( continued )

• Brittle nails and hair , pallor , induration and thickening of skin , periorbital edema , macroglossia , and myxedema .

• Mental status change .• Delayed relaxation time of deep tendon

reflex .• Pleural , peritoneal and pericardial effusion .• Delirium and psychosis .

The Heart in the Hypothyroid State

• Decreased stroke volume , bradycardia , and decreased cardiac output .

• Diastolic hypertension .• Sinus bradycardia and a prolonged PR and

QT intervals .• Low voltage , heart block , T-wave

flattening or inversion , Torsades de pointes , and sudden death .

The Heart in the Hypothyroid State ( continued )

• Echocardiogram may be useful to show regional wall abnormalities .

• It also will diagnose a pericardial effusion .

• Pericardial tamponade is rare .

Laboratory Diagnosis of Hypothyroidism

• Levels of TSH : high .

• The levels of free T4 : decreased .

• Vitamin B 12 deficiency => macrocytic anemia .

• Erythropoietin levels also are low => fall in hematocrit .

• Hyponatremia with low serum osmolality .

Laboratory Diagnosis of Hypothyroidism ( continued )

• Hypoglycemia .

• Cardiac enzymes may be elevated .

• Without AMI , the troponin I level remains normal .

• Adrenal hypofunction .

Laboratory Diagnosis of Hypothyroidism ( continued )

• Elevation of thyroid microsomal antibodies is => chronic autoimmune ( Hashimoto’s ) thyroiditis .

• Thyroid antibodies may be associated with : Grave’s disease , vitiligo , myasthenia gravis , Addison’s disease , pernicious anemia , and other autoimmune diseases .

The Diagnosis of Myxedema Coma

• Abnormal TSH and free T4 values : confirm the diagnosis .( in the presence of nonpitting edema , hypoventilation , hypothermia and stupor )

• Hyponatremia , hypoglycemia , and associated infection : confirmatory .

Precipitating Events for Myxedema Coma

• Surgery , severe infection , and trauma .

• Sedatives , narcotics , and tranquilizers .

• Missed doses of T4 .

Clinical Features of Myxedema Coma

• Alteration in mental status , presence of a precipitating factor , hypothermia , and increased serum CK levels .

• Pale and edematous .

• Respiratory symptoms .

• Ascites , pericardial effusion and pleural effusion .

Clinical Features of Myxedema Coma ( continued )

• Distant heart sounds , bradycardia , high serum cholesterol levels and low voltage on the EKG .

• Dyspnea on exertion , fatigue , and edema .• Distended abdomen , paralytic ileus , and fecal

impaction .• Myxedema megacolon : pseudomembranous

colitis and intestinal ischemia .

Clinical Features of Myxedema Coma ( continued )

• Disturbance in consciousness : ranging from delirium to stupor and coma .

• Hallucination ( myxedema madness ) , cerebellar signs and somnolence .

• Muscle relaxation times of the deep tendon reflexes : delayed markedly .

• Hyponatremia => seizure and depressed level of consciousness .

Laboratory Database of Myxedema Coma

• Serum TSH and free T4 levels , blood glucose , electrolytes , and arterial blood gas .

• Serum cortisol .• Chest films , urinalysis , and blood cultures .• CK , and SGOT .• Serum electrolytes ,creatinine , BUN ,and

glucose should be monitored .

Treatment of Myxedema Coma

• Thyroid hormone replacement : the definitive treatment .

• Intravenous therapy : preferred .• Give steroids when starting thyroid

replacement => avoid precipitating adrenal crisis .

• Passive rewarming and maintenance of appropriate hydration status .

Factors Associated with poor come

• Advantaged age .

• Body temperature lower than 93*F .

• Hypothermia persisting more than three days .

• Bradycardia less than 44 beats/minute .

• Hypotension , MI ,and sepsis .

Initiation of Treatment in ED for Myxedema Coma

• 200-300 mcg ( 4 mcg/kg ) IV bolus thyroxine , followed by 50-100 mcg QD .

• T3 20 mcg IV bolus ( loading dose 10-25 mcg ) , then 10 mcg Q8-12H for 24-48 hours until the patient is conscious and taking maintenance T4 .

• Hydrocortisone 100 mg Q8H .

Initiation of Treatment in ED for Myxedema Coma ( continued )

• Evidence of infection =>Antibiotics .

Underlying illness => Supportive care .

• Consider elective intubation .

• Severe hyponatremia => Consider hypertonic saline .

• Consider appropriate rewarming technique .

Recommendation for Admission for the Hypothyroid Patient

• Clinical diagnosis of myxedema coma => ICU admission .

• Body temperature less than 93*F or bradycardia less than 44 beats /min => ICU admission .

• Comorbidity : CHF ,cachexia , COPD , pneumonia , or any pulmonary problem .

Recommendation for Admission for the Hypothyroid Patient

( continued )

• Underlying disorder : aspiration pneumonia , urosepsis , MI .

• CNS dysfunction : Seizure , ataxia , somnolence , lethargy , confusion , or coma .

• Behavioral disorders : Disorientation , paranoia , or hallucination ( myxedema madness ) .

Recommendation for Admission for the Hypothyroid Patient

( continued )

• Hypoglycemia : suggesting hypopituitarism or adrenal insufficiency .

• Hyponatremia less than 128 mEq/L .

• Social factors that jeopardize patient safety .

Symptoms and Signs of Thyrotoxicosis

• weight loss ( the most common ) , palpitation , weakness , dizziness and syncope .

• Alteration in mental status .

• Heat intolerance .

• Nervous or restlessness .

Symptoms and Signs of Thyrotoxicosis ( continued )

• Tracheal compression => SOB, hoarseness , wheezing and stridor .( Pemberton’s sign )

• Thyromegaly => wheezing , hoarseness , stridor , or dysphagia .

• Myopathy : the proximal muscle groups of the shoulder and pelvic girdles .

Symptoms and Signs of Thyrotoxicosis ( continued )

• Memory loss , confusion and short attention span .

• Chorea , delirium , convulsion , stroke , cerebral venous thrombosis , and coma .

• Some psychiatric conditions => may be mistaken for thyrotoxicosis .

Physical Findings in the Hyperthyroid State

• Flushed skin.Hyperhidrosis of the palms and soles . Alopecia . Fine and brittle hair .

• Fever and tachycardia . • Lid lag , chemosis , exophthalmosis ,

vasodilation of the conjunctiva , edema of the lids , and compromised visual acuity .

• Myxedema of the pretibial areas , feet , and toes .

Physical Findings in the Hyperthyroid State ( continued )

• Diffuse enlargement , bruit , nodules , and tenderness.

• Abdominal pain or secretary diarrhea .

• Muscle weakness , hyperactive reflexes , and tremor .Alteration in mental status .

• Dementia and severe psychomotor retardation . ( Apathetic hyperthyroidism )

The Heart in Thyrotoxicosis

• Diminished diastolic BP . Palpitation .Decreased exercise tolerance . Dyspnea on exertion .Elevated systolic BP . Sinus tachycardia . Atrial fibrillation . Anigina pectoris .

• EKG : shortening of the PR interval , ST change , or atrial fibrillation .

Laboratory Testing in Thyrotoxicosis

• Suppressed TSH levels and increased serum free T4 estimates : clinically evident thyrotoxicosis ( 95% ) .

• Radioactive iodine uptake => incereased .

• ESR => elevated markedly .

• Serum thyroglobulin => increased .

Thyroid Storm

• A life-threatening crisis .

• Estimated mortality : 20-30% .

the result of thyroid surgery .

• Caused more often by antecedent Grave’s disease .

Precipitants of Thyroid Storm

• Surgery .

• Radioiodine therapy .

• Iodinated contrast dyes .

• Thyroid hormone ingestion .

• Diabetic Ketoacidosis .

• Cerebrovascular accident .

• Pulmonary embolism and CHF .

Pathophysiology of Thyroid Storm

• 1) An acute decrease in thyroxine-binding globulin => high levels of free hormone .

• 2) Thyroid hormone increases the density of beta-adrenergic receptors & alters responsiveness to catecholamines at a postreceptor level .

Diagnosis of Thyroid Storm

• Largely a clinical diagnosis .

• CNS disturbances occur in 90% of patients .

• Atrial arrhythmia and ventricular tachyarrhythmia may complicate high output CHF .

• Many of the stigmata of the hyperthyroid state may be present .

Laboratory Diagnosis of Thyroid Storm

• A combination of low TSH and elevated free T4 => makes the diagnosis .

• If TSH is lower than normal and free T4 is normal => free T3 testing is recommended .

ED measurement of thyroglobulin or thyroid antibodies : No indication .

Treatment of Thyroid Storm

• Block hormone synthesis with either :

a) Propylthiouracil 100-600 mg loading PO or NG , 200-250 mg q4h for total daily dose of 1200-1500 mg ; or

b) methimazole 20 mg PO ( 10-40 mg range ) q 4h .

Treatment of Thyroid Storm ( continued )

• Inhibit hormone release :

Iodides –Potassium iodide ( SSKI ) 5 drops PO Q6-8H , or

Lugol’s solution 7-8 drops ( 1 mL PO Q6H ) or

Ipodate 1-3 g daily ( as 1 g Q8H for 24 hours , then 500 mg Q12H ) .

If severe iodide allergy , lithium carbonate 300 mg Q6H .

Treatment of Thyroid Storm ( continued )

• Glucocorticoids : Hydrocortisone ( 300 mg IV , then 100 mg IV q8h ) ; dexamethasone ( 2 mg Q6H ) .

• Adrenergic blockade : Propranolol ( 0.5-3 mg IV over 15 minutes slow IV , then 60-80 mg PO Q4H ) ; Esmolol ( 0.25-0.5 mcg/kg loading , infusion of 0.05-0.1 mcg/kg/min ) .

Adjunctive Therapy for Thyroid Storm

• Treat fever aggressively with acetaminophen .

• IV fluid containing 10% dextrose are recommended .

• Administer vitamin supplements , including thiamine .

• Treat CHF with conventional methods .

Adjunctive Therapy for Thyroid Storm ( continued )

• Identify the precipitating event , including infection .

• Consider plasmapheresis , hemodialysis or peritoneal dialysis for removal of metabolically active hormone .

Admission Criteria for the Hyperthyroid Elderly Patient

• Impending or clinical thyroid storm .• Clinical hyperthyroidism and :• a) CNS effects , including agitation , chorea

, delirium , psychosis , seizure , or coma ;• b) GI effects such as frank diarrhea ,

vomiting , jaundice , dehydration , or abdominal pain ;

Admission Criteria for the Hyperthyroid Elderly Patient

( continued )

• c) Cardiovascular dysfunction , including CHF , sinus tachycardia unresponsive to oral beta blocade in the ED , new onset atrial fibrillation , or angina pectoris ;

• d) Persistent fever > 100.4*F after rest , without source or without easily treatable source ;

• e) Syncopal episode ;

Admission Criteria for the Hyperthyroid Elderly Patient

( continued )

• f) History of recent radioiodinevtherapy ; or

• g) Thyrotoxic periodic paralysis ( address hypokalemia ) .

Underlying precipitating cause .