The likely diagnosis in this case is Haemolytic Uremic Syndrome (HUS), which is generally seen in young children presenting with a triad of symptoms, namely: acute renal failure, microangiopathic haemolytic anaemia, and thrombocytopenia. The typical cause of HUS is ingestion of a strain of Escherichia coli. The laboratory results will usually include fragmented RBCs, decreased serum haptoglobin, reduced platelet count, nonspecific WBC changes, and normal coagulation tests (PTT included).

The duration of these cell cycle phases varies considerably in different kinds of cells. For a typical rapidly proliferating human cell with a total cycle time of 24 hours, the G1 phase might last about 11 hours, S phase about 8 hours, G2 about 4 hours, and M about 1 hour. The proliferation of most animal cells is similarly regulated in the G1 phase of the cell cycle. In particular, a decision point in late G1, called the restriction point in animal cells, is the point at which the cell becomes committed to the cell cycle and after which extracellular proliferation stimulants are no longer required.. Although the proliferation of most cells is regulated primarily in G1, some cell cycles are instead controlled principally in G2.

This is a classic clinical presentation, with alcohol intake and nausea/vomiting that leads to hematemesis, of a Mallory-Weiss tear. Because of the history, that makes this more likely than haemorrhagic gastritis, duodenal ulceration, or oesophagitis (also oesophagitis would not bleed a cupful). Oesophageal varices would present with copious amounts of hematemesis and most likely hemodynamic instability as a result of the amount of blood loss. In Mallory-Weiss tear they are typically presented as a hemodynamically stable patient.

Herpes zoster oticus is a viral infection of the inner, middle, and external ear. It manifests as severe otalgia with associated cutaneous vesicular eruption, usually of the external canal and pinna. When associated with facial paralysis, the infection is called Ramsay Hunt syndrome.

A formula for estimating glomerular filtration rate (eGFR) is the Modification Diet of Renal Disease (MDRD) equation which takes into account the following variables: serum creatinine, age, gender, and ethnicity. Thus, serum urea is not required in this formula.

Triptans are specific 5-HT1 agonists used in the acute treatment of migraine. They are generally used as first-line therapy in combination with an NSAID or paracetamol.

Patients with diabetes often develop ophthalmic complications, the most common and potentially most blinding of these complications is diabetic retinopathy.
The following are the 5 stages in the progression of diabetic retinopathy:
1. Dilation of the retinal venules and formation of retinal capillary microaneurysms.
2. Increased vascular permeability.
3. Vascular occlusion and retinal ischemia.
4. Proliferation of new blood vessels on the surface of the retina.
5. Vitreous haemorrhage and contraction of the fibrovascular proliferation.
The first 2 stages of diabetic retinopathy are known as background or nonproliferative retinopathy. Initially, the retinal venules dilate, then microaneurysms (tiny red dots on the retina that cause no visual impairment) appear. As the microaneurysms or retinal capillaries become more permeable, hard exudates appear, reflecting the leakage of plasma.

Mild nonproliferative diabetic retinopathy (NPDR) or background diabetic retinopathy is indicated by the presence of at least 1 microaneurysm, while neovascularization is the hallmark of Proliferative Diabetic Retinopathy (PDR).

Temporal arteritis is a chronic large- and medium-sized vessel vasculitis that typically involves the temporal arteries. Classical symptoms include temporal headaches, jaw claudication, amaurosis fugax. Physical exam shows scalp tenderness, palpation of the temporal area may demonstrate an absent pulse, knot-like swelling and vision loss. Lab results reveal an increased erythematous sedimentation rate and C-reactive protein. Temporal artery biopsy confirms the diagnosis. Management approach: high-dose systemic corticosteroids should be promptly administered even before the diagnosis is established. Temporal artery biopsy confirms the diagnosis. Inability to manage this or administer glucocorticoids might lead to development of blindness.

Hypogammaglobulinemia occurs due to a variety of underlying primary or secondary immunodeficient states, including HIV which is suspected in this case. The most commonly recognised clinical feature is recurrent infection.

The incubation periods of disorders is extremely important to diagnose, treat, prevent or attenuate a disease.

• Chickenpox: 7-21 days.
• Whooping cough: 10-14 days.
• Hand, foot and mouth disease: 2-6 days.
• German measles: 14-21 days.
• Mumps: 14-18 days.

Contact dermatitis is a red, itchy rash caused by direct contact with a substance or an allergic reaction to it. The entry of allergen into the epidermis or dermis causes a localized allergic reaction. Local mast-cell activation in the skin leads immediately to a local increase in vascular permeability, which causes extravasation of fluid and swelling. Histamine released by mast cells activated by allergen in the skin causes large, itchy, red swellings of the skin.

Cataract is a condition characterized by clouding of the lens of the eye. This condition most frequently occurs due to age-related degenerative processes in the lens, but can also be associated with ocular trauma, metabolic disorders, side-effects of drugs, or congenital infections. The clouding causes distortion of light, as it passes through the lens, resulting in visual impairment and glare. Initially, a cataract presents discretely and may even go unnoticed, but the visual impairment worsens as the cataract grows larger.

Diagnosis is typically established on the basis of a thorough history and direct visualization of the cataract (by means of slit-lamp microscopy). Surgery is indicated with significant visual impairment and involves lens extraction and implantation of an artificial lens. Untreated cataracts eventually lead to complete blindness.

Many drugs are responsible for causing drug induced lupus. However, it is most commonly associated with hydralazine, procainamide and quinidine.

There is a strong suspicion of drug-induced acute tubulo-interstitial nephritis with the classic triad of symptoms of rash, joint pain and eosinophils in the blood, associated with non-specific symptoms of fever and fatigue. This can be confirmed with renal biopsy showing interstitial oedema with a heavy infiltrate of inflammatory cells and variable tubular necrosis.

In general, the aim is to keep the homocysteine (Hcy) concentration as close to normal as possible. In patients who are fully-responsive to pyridoxine, standard doses can lead to tHcy levels below 50 μmol/L (and sometimes within the normal range). Some patients who are partially-responsive to pyridoxine may be able to achieve a tHcy level below 50 μmol/L if they are also on a low-Met diet; for others it is not a realistic goal.

Post-concussion syndrome is a complex disorder in which various symptoms, such as headaches and dizziness, last for weeks and sometimes months after the injury that caused the concussion.

Concussion is a mild traumatic brain injury that usually happens after a blow to the head. It can also occur with violent shaking and movement of the head or body. You don’t have to lose consciousness to get a concussion or post-concussion syndrome. In fact, the risk of post-concussion syndrome doesn’t appear to be associated with the severity of the initial injury.

Post-concussion symptoms include:
Headaches
Dizziness
Fatigue
Irritability
Anxiety
Insomnia
Loss of concentration and memory
Ringing in the ears
Blurry vision
Noise and light sensitivity
Rarely, decreases in taste and smell

This patient presents with the classic triad of renal carcinoma: haematuria, loin pain and a mass in the kidneys. Management will entail right radical nephrectomy because of the 8x8cm solid mass and a left partial nephrectomy of the 3x3cm solid mass.

Refeeding syndrome can be defined as the potentially fatal shifts in fluids and electrolytes that may occur in malnourished patients receiving artificial refeeding (whether enterally or parenterally). These shifts result from hormonal and metabolic changes and may cause serious clinical complications. The hallmark biochemical feature of refeeding syndrome is hypophosphatemia. However, the syndrome is complex and may also feature abnormal sodium and fluid balance; changes in glucose, protein, and fat metabolism; thiamine deficiency; hypokalaemia; and hypomagnesaemia.

Narrow complex tachycardia with hypotension is a medical emergency. Immediate synchronized cardioversion is the ideal management.

Lidocaine is an example of class IB antiarrhythmics.

The Vaughan-Williams classification of antiarrhythmics
I: Membrane stabilizing agents
IA: Quinidine, Procainamide, Disopyramide
IB: Lidocaine, Mexiletine
IC: Propafenone, Flecainide
II: β blockers – Propranolol, Esmolol
III: Agents widening AP – Amiodarone, Dronedarone, Dofetilide, Ibutilide, Sotalol
IV: Calcium channel blockers – Verapamil, Diltiazem
V: Miscellaneous – Digoxin, adenosine, magnesium

The patient presented with sudden-onset headache that is more painful than his usual migraine attacks. This gives a high suspicion of subarachnoid haemorrhage; thus, a CT brain scan should be ordered first to rule this out. However, a normal CT scan is apparent in 30% of patients with subarachnoid haemorrhage and should be referred for lumbar puncture to look for red blood cells.

The principal mechanism of action of taxanes (e.g. docetaxel) is the prevention of microtubule disassembly.

Other aforementioned options are ruled out because:

1. Doxorubicin: stabilizes DNA topoisomerase II complex and inhibits DNA and RNA synthesis.

2. Vincristine, vinblastine: inhibits formation of microtubules.

3. Cisplatin: causes cross-linking in DNA.

In mild-to-moderate heroin overdoses, arterial blood gas (ABG) analysis reveals respiratory acidosis. In more severe overdoses, tissue hypoxia is common, leading to mixed respiratory and metabolic acidosis.

The normal range for PaCO2 is 35-45 mmHg (4.67 to 5.99 kPa). Respiratory acidosis can be acute or chronic. In acute respiratory acidosis, the PaCO2 is elevated above the upper limit of the reference range (i.e., >45 mm Hg) with an accompanying academia (i.e., pH < 7.35). In chronic respiratory acidosis, the PaCO2 is elevated above the upper limit of the reference range, with a normal or near-normal pH secondary to renal compensation and an elevated serum bicarbonate levels (i.e., >30 mEq/L).

Arterial blood gases with pH = 7.31; pCO2 = 7.4 kPa; pO2 = 8.1 kPa would indicate respiratory acidosis.

Drug metabolism can be broadly classified into:
Phase I (functionalization) reactions: also termed non-synthetic reactions, they include oxidation, reduction, hydrolysis, cyclization and de-cyclization. The most common and vital reactions are oxidation reactions. (Of the given enzymes only Alcohol dehydrogenase is involved in phase I drug metabolism. Succinate dehydrogenase, is a vital enzyme involved in the Kreb’s cycle and the mitochondrial electron transport chain). They are mainly catalysed by Cytochrome P-450 enzyme.

Phase II (conjugation) reactions: occur following phase I reactions, they include reactions: glucuronidation and sulphate conjugation, etc. They are mostly catalysed by UDP-glucuronosyltransferase enzyme. Other phase II enzymes include: sulfotransferases, N-acetyltransferases, glutathione S-transferases and methyltransferases.

Lead poisoning is characterised by abdominal pain, fatigue, constipation, peripheral neuropathy (mainly motor), and blue lines on gum margin in 20% of the adult patients (very rare in children).

For diagnosis, the level of lead in blood is usually considered with levels greater than 10 mcg/dL being significant. Furthermore, the blood film shows microcytic anaemia and basophilic stippling of red blood cells. Urinary coproporphyrin is increased (urinary porphobilinogen and uroporphyrin levels are normal to slightly increased). Raised serum and urine levels of delta-aminolaevulinic acid may also be seen, making it sometimes difficult to differentiate from acute intermittent porphyria.

Klinefelter syndrome (KS), the most common human sex chromosome disorder 47,XXY. It is characterized by hypogonadism (micro-orchidism, oligospermia/azoospermia) and gynecomastia in late puberty. If Klinefelter syndrome is not diagnosed prenatally, a patient with 47,XXY karyotype may demonstrate various subtle, age-related clinical signs that would prompt diagnostic testing. These include the following:
Infants: Hypospadias, small phallus, cryptorchidism.
Toddlers: Developmental delay (especially expressive language skills), hypotonia.
Older boys and adolescent males: Tall stature; delayed or incomplete pubertal development with eunuchoid body habitus; gynecomastia; small, firm testes; sparse body hair.

From childhood with progression to early puberty, the pituitary-gonadal function observed is within normal limits for 47,XXY males.
At mid puberty and later, follicle-stimulating hormone (FSH) and luteinizing hormone (LH) concentrations rise to hyper-gonadotropic levels, inhibin B levels fall until they are undetectable, and testosterone levels are at low or low-normal levels after an initial increase.

Fragile X syndrome, also termed Martin-Bell syndrome or marker X syndrome, is the most common cause of inherited mental retardation, intellectual disability, and autism.
However, the patient here does not have any mental disabilities as he already works as a clerk, and that too would make Down’s Syndrome less likely.

Classic Kallmann syndrome (KS) and idiopathic hypogonadotropic hypogonadism (IHH) are rare genetic conditions that encompass the spectrum of isolated hypogonadotropic hypogonadism. Most patients have gonadotropin-releasing hormone (GnRH) deficiency, as suggested by their response to pulsatile GnRH therapy. Hypothalamic-pituitary function is otherwise normal in most patients, and hypothalamic-pituitary imaging reveals no space-occupying lesions. By definition, either anosmia or severe hyposmia is present in patients with Kallmann syndrome, in contrast to patients with idiopathic hypogonadotropic hypogonadism, whose sense of smell is normal.

West Nile virus is an RNA virus transmitted by the Culex species of mosquitoes. It is mostly prevalent in South America, Africa and some parts of Europe. Clinically it presents with high grade fever, headache, abdominal pain, anorexia and a morbilliform rash over the body. It can also lead to meningitis, encephalitis and flaccid paralysis by affecting the anterior horn cells, a process suggesting similarity to poliomyelitis. It can be fatal if not treated abruptly. Studies suggest that it can be transferred from mother to offspring. New-borns may present with encephalitis, chorioretinitis and wide spread brain damage. Patients suffering from West Nile virus can be effectively treated with interferon, IV immunoglobulin and Ribavirin.

Extrinsic allergic alveolitis (EAA) refers to a group of lung diseases that can develop after exposure to certain substances. The name describes the origin and the nature of these diseases:

‘extrinsic’ – caused by something originating outside the body
‘allergic’ – an abnormally increased (hypersensitive) body reaction to a common substance
‘alveolitis’ – inflammation in the small air sacs of the lungs (alveoli)

Symptoms can include: fever, cough, worsening breathlessness and weight loss. The diagnosis of the disease is based on a history of symptoms after exposure to the allergen and a range of clinical tests which usually includes: X-rays or CT scans, lung function and blood tests.

EAA is not a ‘new’ occupational respiratory disease and occupational causes include bacteria, fungi, animal proteins, plants and chemicals.

Examples of EAA include:

Bird fancier’s lung (BFL) is a type of hypersensitivity pneumonitis (HP). It is triggered by exposure to avian proteins present in the dry dust of the droppings and sometimes in the feathers of a variety of birds. The lungs become inflamed, with granuloma formation. Birds such as pigeons, parakeets, cockatiels, shell parakeets (budgerigars), parrots, turtle doves, turkeys and chickens have been implicated.

People who work with birds or own many birds are at risk. Bird hobbyists and pet store workers may also be at risk. This disease is an inflammation of the alveoli in the lungs caused by an immune response to inhaled allergens from birds. Initial symptoms include shortness of breath (dyspnoea), especially after sudden exertion or when exposed to temperature change, which can resemble asthma, hyperventilation syndrome or pulmonary embolism. Chills, fever, non-productive cough and chest discomfort may also occur.

A definitive diagnosis can be difficult without invasive testing, but extensive exposure to birds combined with reduced diffusing capacity are strongly suggestive of this disease. X-ray or CT scans will show physical changes to the lung structure (a ground glass appearance) as the disease progresses. Precise distribution and types of tissue damage differ among similar diseases, as does response to treatment with Prednisone.

DGI presents as two syndromes: 1) a bacteremic form that includes a triad of tenosynovitis, dermatitis, and polyarthralgias without purulent arthritis and 2) a septic arthritis form characterized as a purulent arthritis without associated skin lesions. Many patients will have overlapping features of both syndromes. Time from infection to clinical manifestations may range from 1 day to 3 months. There is no travel history and the rash of Lyme disease is not purulent. Reactive arthritis presents with conjunctivitis, urethritis and arthritis usually with a red hot tender and swollen joint.

The two statements that fit the characteristics of doxapram are, epilepsy is a contraindication for doxapram use and concurrent use with theophylline may increase agitation.

Doxapram is a central respiratory stimulant. In clinical practice, doxapram is usually used for patients who have an acute exacerbation of chronic obstructive pulmonary disease (COPD) who are unsuitable for admission to the intensive therapy unit for ventilatory support. Doxapram infusion may buy an extra 24 h to allow for recovery.

Contraindications include: ischaemic heart disease, epilepsy, cerebral oedema, acute stroke, asthma, hypertension, hyperthyroidism, and pheochromocytoma.
The infusion may worsen agitation and dyspnoea and lead to hypertension, nausea, vomiting and urinary retention.

Drug interactions:
Concomitant administration of doxapram and aminophylline (theophylline) can cause increased skeletal muscle activity, agitation, and hyperactivity.