geekymedics

• ABPI is the ratio of SBP in the ankle to the SBP in the upper arm (brachium). In a healthy person, both pressures should be similar so a normal value would be between 0.9-1.2. An ABPI of <0.9 can indicate PAD. A common symptom of PAD is intermittent claudication, which is a cramp-like pain, felt in the calf during exertion and relieved by rest.

  ABPI is calculated using the highest values in the following equation.

  ABPI = SBP of the ankle / SBP of the arm
• Hypothyroidism reduces the basal metabolic rate, leading to cold intolerance and reduced core temperature as less heat is produced as a by-product of metabolism.
• Mean cell volume: Macrocytosis is found in up to 60% of patients with hypothyroidism and can result from deficiencies in either thyroid hormone itself, or in vitamin B12 (Pernicious anaemia occurs 20 times more frequently in patients with hypothyroidism). The other main type of anaemia seen in hypothyroidism is normocytic anaemia, as thyroid hormone stimulates the production of erythropoietin (EPO) in the kidney. Therefore, it is unlikely that this gentleman with poorly managed hypothyroidism would have a low MCV, but rather it would be high or normal.
• LDL Cholesterol: One of the major reasons for treating hypothyroidism is that it leads to a significant rise in serum LDL Cholesterol, which causes atherosclerosis and premature heart disease. The rise in LDL can be explained by a reduction in circulating T3, which at normal concentrations up-regulates the LDL-receptor, allowing LDL cholesterol to be catabolised. 
• TSH: In primary hypothyroidism, TSH levels should increase due to the loss of negative feedback of thyroid hormones on the pituitary. Therefore, TSH would likely be high in this man who has poorly managed primary hypothyroidism.
• Body mass index: Hypothyroidism causes an increase in BMI due to a reduction in basal metabolic rate, which decreases calorific expenditure and subsequently causes weight gain. Therefore, BMI would likely be high in this man who has poorly managed hypothyroidism.
• Dabigatran is an anticoagulant, not an antiplatelet agent. More specifically, it is a direct thrombin inhibitor.

  Aspirin is an antiplatelet agent. More specifically, it is a cyclo-oxygenase inhibitor, which works by inhibiting formation of thromboxane from arachidonic acid, thereby reducing platelet aggregation.

  Clopidogrel, prasugrel and ticagrelor are also antiplatelet agents. More specifically, they are ADP-receptor antagonists (P2Y12 subtype), which work by inhibiting platelet activation and aggregation.
• Tumour lysis syndrome is a potentially fatal complication of chemotherapy for malignancy (most commonly seen in patients with lymphoma or leukaemia).

  Tumour lysis syndrome is a group of metabolic disturbances including:

  • Hyperkalaemia
  • Hyperphosphataemia
  • Hyperuricaemia
  • Hypocalcaemia

  These can lead to serious complications such as acute renal failure, cardiac arrhythmias and seizures.

  TLS is not generally associated with changes to sodium
• In patients presenting with aortic stenosis, the most common triad is SAD, which stands for syncope, angina and dyspnoea. It takes many years for the development of aortic stenosis and patients are initially asymptomatic. The low volume, slow rising pulse, which is also known as ‘pulsus parvus et tardus’, is quite suggestive of aortic stenosis. Another suggestive feature of aortic stenosis in this patient is the ejection systolic murmur which radiates to the carotid artery. 
• Aortic regurgitation happens when the aortic heart valve is incompetent, and blood flows back from the aorta to the left ventricle during diastole. The pulse is often described as a ‘water hammer’ pulse and the patient may have a wide pulse pressure. The widened pulse pressure is due to increased stroke volume. Sometimes, patients with aortic regurgitation have a prominent carotid pulsation known as “Corrigan’s sign”. On auscultation, there is a decrescendo diastolic murmur, which typically radiates to the lower left sternal edge. 
• A prolonged PR interval with broad, bizarre QRS complexes that merge with both the preceding P wave and the subsequent T wave and peaked T waves, are indicative of hyperkalemia, which could be confirmed with serum urea and electrolytes. The patient needs immediate treatment of his elevated potassium by stabilising his myocardium with calcium gluconate. The hyperkalaemia can then be treated with an insulin and glucose infusion, shifting potassium into the intracellular space. 

  Salbutamol can also be used in a similar manner, with definitive treatment focusing on reversing his AKI.
• Spironolactone is a potassium-sparing diuretic, which would worsen the patient's hyperkalaemia.
• Ibuprofen has the potential to worsen this man's acute kidney injury and therefore should not be used.
• Ramipril, an ACE-inhibitor, has been shown to exacerbate acute kidney injury and also worsen hyperkalaemia in some cases of patients with chronic kidney disease.
• Movicol is a laxative that contains potassium as a sweetener and carries the risk of further worsening this patient's hyperkalaemia.
• Heat intolerance (due to the increase in non-shivering thermogenesis), onycholysis (detachment of nails from the nail bed), diarrhoea, weight loss, increase in appetite along with general agitation/anxiety are hallmarks of hyperthyroidism. Even though there is typically weight loss in overactive thyroid conditions, 10% paradoxically gain weight due to the increased appetite. 
• A pheochromocytoma is an adrenaline producing tumour of the chromaffin cells in the adrenal medulla. It classically presents with a triad of headaches, palpitations and sweating.
• Hypothyroidism (e.g. Hashimoto's thyroiditis) is likely to present with lethargy rather than agitation, and cold intolerance rather than feeling hot. (i.e. many layers of clothing on a warm day). 
• Alpha-1 antitrypsin (A1AT) deficiency is a co-dominant genetic disorder, with dyspnoea and a chronic cough. The lack of A1AT enables neutrophil elastase to break down elastin in the lungs causing emphysema which especially affects the lower lobes. Tram-track lines suggest bronchiectasis. A1AT is often mistaken for asthma. In some forms (e.g. the PiMZ genotype, his mother is well - PiMM, and father is ill - PiZZ) symptoms are precipitated/exacerbated by environmental insults (smoking, dust inhalation). Emphysema is secondary, implied by age 35, family history, and only 2 pack-years of smoking.
• Primary hyperthyroidism involves an excessive production of T3 and T4 by the thyroid gland as a result of pathology within the thyroid gland itself. The pathophysiology is as follows:

  1. The thyroid produces excessive amounts of T4 and T3.
  2. The excessive T4 and T3 cause negative feedback on the pituitary and hypothalamus, resulting in decreased production of TRH and TSH.
  3. The end result is a raised T3 and T4 and a low TSH.
• A TSH-secreting tumour would cause a raised TSH, T3 & T4.

  In primary hypothyroidism, TSH is typically raised in response to a low T3 and T4.

  In secondary hypothyroidism, TSH secretion is reduced resulting in low TSH, T3 and T4.
• Classic findings of heart failure ABCDE:

  • A - Alveolar oedema (bat wing opacities); not shown on this image
  • B - Kerley B lines (horizontal lines in the periphery of the lower posterior lung fields)
  • C - Cardiomegaly (seen as an increased cardiothoracic ratio; i.e. the cardiac diameter is > 0.5 the width of the thorax.)
  • D - Dilated upper lobe vessels ('cephalization')
  • E - Pleural effusion (shown as 'blunting' of the costophrenic angles or fluid in the fissures between lobes of the lung)

  
• Diverticular disease, including diverticulosis and diverticulitis, is primarily associated with a low-fibre diet which can lead to increased colonic pressure, which contributes to the development of diverticula (outpouchings of the colon wall). These diverticula can become inflamed (diverticulitis).

  Age, obesity, smoking, and family history are risk factors but it not the primary factor. Most individuals over the age of 60 have diverticula, but not all of them develop diverticulitis.
• Findings that would suggest a renal mass, rather than splenic, include:

  • Movement towards the left iliac fossa on inspiration (vertically downward)
  • No palpable notch
  • Able to feel upper border
  • Ballotable
  • Resonant to percussion (due to overlying bowel)
• Patients of African or Caribbean descent are prone to developing low-renin, salt-sensitive type hypertension, therefore beta-blockers (e.g. bisoprolol) or ACE inhibitors (e.g. ramipril) are less effective than low-dose diuretics or calcium channel blockers. As such current NICE guidelines recommend calcium-channel-blockers (CCBs) in patients over 55 years and to patients of African or Caribbean family origin of any age. If CCBs are not suitable (e.g. significant side effects such as oedema or evidence/high risk of heart failure) thiazide-like diuretics should be used. 
• Candesartan is an angiotensin receptor blocker that is typically prescribed when patients have side effects from ACE inhibitors.

  Doxazosin is an alpha-blocker that can be used to treat hypertension, however, it would not be prescribed as a first-line medication.
• Some tricyclic medications can cause prolongation of the QT interval: amitryptiline. Other drugs with this side effect include certain SSRIs, SNRIs and antipsychotics.

  Sodium valproate, ethambutol, doxycycline and bisoprolol do not cause prolongation of the QT interval.
• Classical clinical signs of acute pericarditis – central chest pain worse on inspiration and when lying flat but relieved by sitting forward. ECG changes are widespread PR depression and concave ST elevation. Acute pericarditis (inflammation of the pericardium) can be idiopathic or secondary to multiple causes; most commonly viral infections such as influenza. A pericardial friction rub may be heard on auscultation, or there may be evidence of a pericardial effusion (muffled heart sounds) but often heart sounds are normal.
• QRS widening is not a feature of pericarditis. 

  Pericarditis is associated with PR segment depression and widespread ST elevation with reciprocal changes in aVR (occurs during the first couple of weeks)

  Associated T wave flattening can also be seen from weeks 1 to 3. 

  Sinus tachycardia is also seen in some cases due to the chest pain.
• Total Anterior Circulation Strokes are associated with all of the following 

  • Unilateral hemiparesis and/or hemi-sensory loss of face, arms and leg 
  • Homonymous hemianopia
  • Higher cognitive dysfunction eg expressive and receptive dysphasia, visual and sensory inattention, neglect

  Loss of consciousness is associated with a posterior circulation stroke 
• Acute limb ischaemia occurs when there is a sudden drop in perfusion of the limb, threatening the viability of the limb. It typically presents with the symptoms and signs of the 6 Ps: pallor, paraesthesia, pain, pulseless, perishingly cold, and paralysis. The symptoms will be sudden onset if due to an embolus; a risk factor for this would be atrial fibrillation as implied in the question stem.
• Acute viral hepatitis - RUQ tenderness, jaundice, deranged LFTs (specifically, the markedly elevated transaminases AST & ALT), and pyrexia.
• An obstructive liver injury caused by a cholangiocarcinoma -elevation of GGT and ALP, rather than elevated transaminases
• In order to suspect Budd-Chiari syndrome (BCS), a patient needs to present with a classic tetrad - namely: abdominal pain, ascites, liver enlargement, and splenomegaly. The patient would need to be in somewhat of a hypercoagulable state to rule in primary BCS (as it is caused by hepatic vein thrombi). Synthetic liver dysfunction (hypoalbuminaemia) would lead to ecchymoses (failure of the liver to synthesis clotting factors).
• The presence of Streptococcus bovis is associated with colorectal carcinoma, and investigation with colonoscopy should be considered.
• Complete heart block is suggestive of damage to the AV node. In 80-90% of the population, the AV node is supplied by a branch of the right coronary artery (the atrioventricular nodal branch). The right coronary artery supplies the right atrium and ventricle, as well as the SA and AV nodes.

  The left circumflex artery is also a possibility for complete heart block in the remaining 10-20% of the population.
• Arrhythmia is the most common complication in the first 4 to 24 hours after a myocardial infarction. Coagulative necrosis damages the heart’s conduction system, increasing the risk of arrhythmias.
• Glomerulonephritis, describes inflammation and damage to the glomeruli of the kidneys causing leakage of protein and/or blood into the urine (proteinuria and haematuria, respectively). The pinkish colour of the urine likely indicates the presence of blood, whilst the frothiness indicates the presence of protein. Glomerulonephritis is known to cause hypertension in several patients. The pyrexia and high respiratory rate demonstrated by the patient are consistent with an infectious or inflammatory process. 

  In contrast, nephrotic syndrome presents with proteinuria without haematuria.
• Adrenal insufficiency presents with features such as muscle weakness, fatigue, loss of appetite, weight loss and abdominal pain. 

  Conn’s syndrome (primary hyperaldosteronism) presents with excessive thirst, frequent urination, fatigue and weakness, and perinephric abscesses present with flank pain and constitutional symptoms, sometimes with haematuria but without proteinuria.
• GLP-1 analogues (-tides) and DPP IV inhibitors (-gliptins) can be continued on the day of surgery.

  The morning dose should be omitted on the day of surgery for patients taking sulfonylureas and SGLT-2

  Patients on twice-daily biphasic routines or taking ultra-long acting insulins (e.g. Novomix 30) should halve their usual morning dose on the day of surgery.

  Medications such as St. Johns Wort and clopidogrel should be discontinued 7 days pre-operatively. 

  Patients on once-daily insulin routines (e.g. taking Lantus or Levemir) should reduce their dose by 20% on the morning of surgery.