Hyperthyroidism

Thyroid overactivity, thyrotoxicosis
> common condition
> commonly affect women, age between 20 - 40 years old
> common hyperthyroidism conditions: Graves' disease. toxic multinoduular goitre, toxic adenoma, de
                                                           Quervain's thyroiditis, postpartum thyroiditis
> Clinical features -
    Symptoms:
    - weight loss                    - muscle weakness       - itching                  
    - increased appetite         - stiffness                      - thirst                  
    - irritability                       - malaise                      - vomiting              
    - restlessness                   - choreoathetosis          - diarrhoea            
    - tremor                          - breathlessness             - eye complaints    
    - heat intolerance             - palpitation                  - goitre                  
    - oligoamenorrhoea         - loss of libido               - gynaecomastia
    - onycholysis                   - sweating                     - tall stature (in children)
   Signs:
    - tremor                                        - psychosis                                
    - hyperkinesia                               - systolic hypertension          
    - tachycardia or atrial fibrillation     - cardiac failure                  
    - full pulse                                     - conjunctival oedema        
    - warm peripheries                        - ophthalmoplegia              
    - exophthalmos                             - periorbital oedema
    - lid lag and 'stare'                         - weight loss
    - goitre, carotid bruit                     - proximal myopathy
    - onycholysis                                 - palmar erythema
    - Graves' dermopathy                    - Thyroid acropacity
    - pretibial myxoedema

> Investigations:
   - Serum TSH: low (< 0.05 mU/L)
   - Elevated free T4 and t3 hormones
   - Presence of microsomal and thyroglobulin antibodies in Graves' disease
   - Ultrasound: differentiate Graves' disease from toxic adenoma

> Management
1) Antithyroid drugs
     - carbimazole, methimazole
     - block thyroid biosynthesis
     - side effects: agranulocytosis
     - if toxicity occurs, propylthiouracil
2) Beta blockers
     -  to provide rapid symptomatic control
3) Radioactive iodide
     - Iodine - 131
     - contraindicated in pregnancy and in breast-feeding mother
     - accumulates in gland and results in irradiation and tissue damage
4) Surgery
     - subtotal thyroidectomy indicated in patients that rendered euthyroid
     - complications: bleeding, hypocalcemia, hypothyroidism, hypoparathyroidism, recurrent laryngeal nerve
        palsy, recurrent hyperthyroidism
     - indications: large goitre, drug side-effects, poor compliance, defaulted radioiodine, suspicion of
                         malignancy

Atrial Fibrillation

- Characterized by an irregular and often rapid heartbeat

- strongly associated with heart failure, coronary artery disease, valvular heart disease, diabetes mellitus, hypertension

History:

 - 90% of AF are asymptomatic

 - wide range of symptoms: palpitations, dyspnoea, fatigue, dizziness, angina, decompensated heart failure

 - history should include: 

                  + type, duration and frequency of symptoms

                  + precipitating factors

                  + modes of termination

                  + documentation of prior use of anti-arrhythmics and rate-controlling agents

                  + presence of underlying heart disease

                  + history of any previous surgical or percutaneous AF ablation procedures

Physical examination:

 - Vital signs: irregularly irregular pulse, tachycardic

 - Head and neck: exophthalmos, thyromegaly, elevated jugular venous pressure, cyanosis, carotid artery bruits

 - Pulmonary: rales, pleural effusion, wheeze

 - Cardiac: displaced apex beat, prominent P2 points

 - Abdomen: ascites, hepatomegaly, hepatic capsular tenderness, splenic infarct

 - Lower extremities: cyanosis, clubbing, oedema, pulseless extremity

 - Neurologic: signs of transient ischaemic attack or cerebrovascular accident, increased reflex

Differential Diagnosis:

- Atrial flutter

- Atrial tachycardia

- Atrioventricular Nodal Reentry Tachycardia

- Multifocal Atrial Tachycardia

- Paroxysmal Supraventricular Tachycardia

- Wolff-Parkinson-White Syndrome

Investigation: 

1) Electrocardiography

    

                            - Rate irregularly irregular, 110-140 bpm

                            - No P waves

                            - Irregular baseline

                            - Normally shaped QRS complexes

                            - Lead V1 - no flat baseline between P waves

2) Laboratory studies

• Complete blood count - look for anaemia or infection
• Serum electrolyte and blood urea nitrogen/creatinine ratio - electrolyte disturbances or renal failure
• Cardiac enzymes - CK and/ or troponin level - investigate myocarcial infaction
• B-type Natriuretic Peptide - to evaluate congestive heart failure
• D-dimer - if the patient has risk factors for pulmonary embolism
• Thyroid function studies - to look for thyrotoxicosis
• Digoxin level - toxicity level

3) Echocardiography

• evaluate for valvular heart disease
• evaluate for left and right size
• evaluate for left ventricular size and function and left ventricular hypertrophy
• evaluate for pericardial disease

4) Computed Topography and Magnetic Resonance Imaging

• Chest CT angiography to rule out pulmonary embolism
• 3D imaging technique are helpful to evaluate atrial anatomy for intervention

5) Chest radiography

• evidence of congestive heart failure
• signs of lung pathology i.e. pulmonary embolism, pneumonia

6) Stress test - to rule out inschemia