Adult Medical-Surgical Nursing Endocrine Module: Hypersecretion of the Thyroid

Secretions of the Thyroid Gland  The thyroid secretes Thyroglobulin, the pre-cursor of:  Thyroxine (T4)  Tri-odothyronine (T3) (more potent)  (under control of Hypothalamus → TSH from Anterior Pituitary)  Also Calcitonin

Functions of Thyroid Hormones  T3 and T4:  Energy metabolism and moderation of Basal Metabolic Rate (BMR): oxygen uptake and consumption at cellular level  Cell replication and growth  Brain and nervous development/ function  Calcitonin: Regulation of serum calcium (lowers while Parathormone raises)

Importance of Iodine for Thyroid Function  Iodine is essential to the thyroid for synthesis of hormones (major uptake and use of iodine in the body)  Iodine in fish, added to salt, mostly in H2O  Iodine from diet + Tyrosine (amino acid) → T3 and T4  ↓ iodine in diet leads to ↓ thyroid function  Most important cause of hypothyroidism world-wide and enlargement (Goitre)

Hyperthyroidism: Grave’s Disease (Thyrotoxicosis)  Increased synthesis and release of thyroid hormones  Affects metabolism increasing BMR  Auto-immune condition  Aetiology:  Genetic tendency  Unknown aetiology  Exacerbated by stress, infection, ↓ iodine

Hyperthyroidism (Auto-immune)  Thyroid-stimulating antibodies act like TSH stimulating thyroid:  Hyperplasia  Hypersecretion  Leads to gradual destruction of gland, and eventually to exhaustion, atrophy and hyposecretion, requiring HRT

Hyperthyroidism: Pathophysiology  Hyperplasia: thyroid enlargement (“toxic goitre” as hypersecretion)  Hypersecretion: increased thyroid hormone → increased BMR  ↑ tissue sensitivity to sympathetic stimulation (adrenoline/ noradrenaline)  Ophthalmopathy: impaired venous drainage from the eye orbit (auto-immune effect), fat deposits and orbital oedema

Hyperthyroidism: Clinical Manifestations (Thyrotoxicosis)  Goitre with increased pressure on trachea  Excitability, restlessness, nervousness, tremor  Rapid weight loss  Much increased appetite and thirst  Fatigue from over-activity → muscle weakness and exhaustion  Cannot tolerate heat, flushed, sweating

Hyperthyroidism: Clinical Manifestations (cont)  Tachycardia/ tachypnoea: bounding very rapid pulse (90 – 160/min)  Increased resting pulse  Palpitations (dysrhythmias) and increased pulse pressure  ↑ peristalsis, diarrhoea, frequent stools  Exophthalmos: staring, protruding eyes (vision not affected)

Hyperthyroidism: Diagnosis  History and clinical picture  Immuno-assay or radio-assay of hormone levels: TSH, T3 and T4 and FT4 (free unbound thyroxine)  Radio-active iodine uptake test  Needle biopsy of thyroid  Ulrasound scan  ECG

Hyperthyroidism: Medical Management  Anti-thyroid medication (Carbimazole* or Propylthiouracil): inhibit synthesis of thyroid hormones by blocking utilisation of iodine until “euthyroid state” (non-toxic)  Radio-active iodine (I 131 ) gradually destroys some of thyroid cells. (Patient must be euthyroid prior. May need 2 treatments. Risks hypothyroidism)

Hyperthyroidism: Surgical Management  Sub-total thyroidectomy (small amount of tissue left to regenerate slowly)  Leaves parathyroid glands intact  Avoids damage to recurrent laryngeal nerve  Pre-op: Patient must be in euthyroid condition prior to surgery, prepared with anti-thyroid drugs, iodine ( ↓ size / vascularity) and B - blockers (Propanalol)

Sub-total Thyroidectomy: Risks related to surgery  Airway obstruction from:  Oedema and pressure on trachea or stridor (damage and oedema to recurrent laryngeal nerve)  Bleeding and haematoma (very vascular)  Damage/ removal of parathyroids → low blood calcium levels (Tetany)  Thyroid crisis (hyperpyrexia, extreme tachycardia and dysrhythmias, delirium)

Hyperthyroidism: Nursing Considerations  Patient education  Monitoring/ supervision during tests  Pre- and post-operative care especially be prepared for any post-op emergency:  At bedside, O2 and suction ready and clip- removers  Semi-sitting position, well-supported with pillows  Careful monitoring all vital signs, wound.