Endocrine

Question 1

Thyroid hormone (T3 and T4)

Answer 1

Thyroid hormone

• regulate basal metabolic rate
  
  • by increasing, body temperature also increases
  • thyroid affects numerous other processes, affecting nearly every cell in th body
• life-long medication management of thyroid issues
• DO NOT suddenly stop medication - can send them into crisis
• hypothalamus secretes TRH –> TRH stimulates pituitary gland to secrete TSH –> TSH stimulates thyroid gland to secrete T3 and T4
  
  • negative feedback system - as thyroid hormone levels increase, negative feedback supresses the secretion of TSH and TRH.
  • High levels of iodine can also cause a temporary decrease in thyroid activity that can last for several weeks

Hypothyroidism

• Cause: results from either a poorly functioning thyroid gland or low secretion of TSH by the pituitary gland
  
  • Most common cause: Hashimoto’s thyroiditis or chronic autoimmune thyroiditis - results in destruction of the thyroid gland
• Clinical Manifestation:
  
  • early symptoms: general weakness, muscle cramps, dry skin
  • more severe symptoms: slurred speech, bradycardia, weight gain, decreased sense of taste and smell, intolerance to cold enviroinments
  • Goiter may be absent or preesent depending on the cause of disease
  • Lab results generally revealed elevated TSH with diminished T3 and T4 levels
• Tx: levothyroxine (Synthroid, Levothroid)
  
  • take on EMPTY stomach in MORNING
  • do not take SOY PRODUCTS w/in 1 - 4 hrs
  • do not take CALCIUM w/in 4 hrs
  • Watch iodine
• Contraindications: use for weight loss
• Misc. Management:
  
  • serum TSH levels used to eval progress of therapy
  • avoid switching bands of medicatin once condition has stabilized

Hyperthyroid

• Causes:
  
  • Most common type of hyperthyroidism: Graves’ Disease - autoimmune disease;
  • Other causes are adenomas of the thyroid, pituitary tumors, and pregnancy
• Hypersecretion of thyroid hormones:
  
  • increased body metabolism, weight loss
  • tachycardia, elevated body temp
  • anxiety
• If left untreated, can cause thyroid storm
  
  • s/s:
    
    • high fever
    • CV effects (tachycardia, heart failure, angina, MI)
    • CNS effects (agitation, restlessness, delirium, progressing to coma)
• Treatment:
  
  • surgical removal of part or all of thyroid gland
  • antithyroid drugs - hepatotoxic
    
    • methimazole (tapazole)
      
      • NOT BABY SAFE; pregnancy D
        
        • if pregnant notify physician asap
    • propylthiouracil (PTU)
      
      • BABY SAFE

Question 2

antidiuretic hormone (ADH)

Answer 2

• posterior pituitary gland directly secretes ADH that acts on collecting ducts of kidneys to increase water reabsoprtion
  
  • ADH
    
    • regulates body fluid
    • acts as vasoconstrictor
• Deficiency of ADH
  
  • diabetes insipidus - production of large volumes of very dilute urine
  • S/S:
    
    • polyuria -
    • polydipsia -
  • Tx:
    
    • acts on kidneys to help reabsorb water, reduce urination → increase reabsoprtion of water
    • desmopressin
      
      • make sure sodium levels are normal before administering, otherwise may use other drug
    • vasopressin
  • Monitor:
    
    • blood pressure (increase circulatory volume → increased BP, increased HR)
      
      • monitor esp. if underlying CV issues
  • Precaution: acute or chronic renal disease