Atrial natriuretic peptide (ANP) is a 28-amino acid peptide that is synthesized, stored, and released by atrial myocytes in response to atrial distension, angiotensin II stimulation, endothelin, and sympathetic stimulation (beta-adrenoceptor mediated). ANP is synthesized and secreted by cardiac muscle cells in the walls of the atria in the heart. The main physiological actions of natriuretic peptides is to reduce arterial pressure by decreasing blood volume and systemic vascular resistance. It causes a reduction in expanded extracellular fluid (ECF) volume by increasing renal sodium excretion.

Physiological abnormalities in anorexia include:
– Hypokalaemia – from diuretic or laxative use
– Low FSH, LH, oestrogens and testosterone – most consistent endocrine abnormality was low serum luteinizing and follicle stimulating hormone (LH and FSH) levels associated with depressed serum oestradiol levels.
– Raised cortisol and growth hormone
– Impaired glucose tolerance – lack of glucose precursors in the diet or low glycogen stores. Low blood glucose may also be due to impaired insulin clearance
– Hypercholesterolemia
– Hypercarotenaemia
– Low T3

Thrombotic thrombocytopenic purpura (TTP) is characterised by the von Willebrand factor (vWF) microthrombi within the vessels of multiple organs. In this condition, the ADAMTS13 metalloprotease enzyme which is responsible for the breakdown of vWF multimer, is deficient, causing its build-up and leading to platelet clots that then decreases the circulating platelets, leading to bleeding in the patient.

Streptococcus pneumonia is the chief causative organism for lobar pneumonia in this age group patients. Typically patients present with rusty coloured sputum and a cough. Pneumocystis jiroveci is responsible for causing pneumocystis pneumonia among immunocompromised patients.

Anticholinergic syndrome occurs following overdose with drugs that have prominent anticholinergic activity including tricyclic antidepressants, antihistamines and atropine. Features include dry, warm, flushed skin, urinary retention, tachycardia, mydriasis (dilated pupils) and agitation.

The patient is most likely to have Medullary Thyroid Carcinoma (MTC).
Sporadic, or isolated MTC accounts for 75% of cases and inherited MTC constitutes the rest.
Inherited MTC occurs in association with multiple endocrine neoplasia (MEN) type 2A and 2B syndromes, but non-MEN familial MTC also occurs.
A 24-hour urinalysis for catecholamine metabolites (e.g., vanillylmandelic acid [VMA], metanephrine) has to be done to rule out concomitant pheochromocytoma in patients with MEN type 2A or 2B, as Pheochromocytoma must be treated before MTC.

The most probable diagnosis is Marfan’s syndrome because of a family history of cardiac death and heart murmurs. A characteristic feature is pain which radiates to the back. A wide pulse pressure and a diastolic heart murmur is suggestive of aortic dissection.

This patient has developed a venous sinus thrombosis peri-partum, resulting in her symptoms. Anticoagulation therapy including Heparin improves outcomes.

Mechanism of action of low molecular weight heparin (LMWH):
It inhibits coagulation by activating antithrombin III. Antithrombin III binds to and inhibits factor Xa. In doing so it prevents activation of the final common path; Xa inactivation means that prothrombin is not activated to thrombin, thereby not converting fibrinogen into fibrin for the formation of a clot.

LMHW is a small fragment of a larger mucopolysaccharide, heparin. Heparin works similarly, by binding antithrombin III and activating it. Heparin also has a binding site for thrombin, so thrombin can interact with antithrombin III and heparin, thus inhibiting coagulation.
Heparin has a faster onset of anticoagulant action as it will inhibit not only Xa but also thrombin, while LMWH acts only on Xa inhibition.

Compared to heparin, LMWHs have a longer half-life, so dosing is more predictable and can be less frequent, most commonly once per day.

Dosage and uses:
LMWH is administered via subcutaneous injection. This has long-term implications on the choice of anticoagulant for prophylaxis, for example, in orthopaedic patients recovering from joint replacement surgery, or in the treatment of DVT/PE.

Adverse effects:
The main risk of LMWH will be bleeding. The specific antidote for heparin-induced bleeding is protamine sulphate.
Less commonly it can cause:
Heparin-induced thrombocytopenia (HIT)
Osteoporosis and spontaneous fractures
Hypoaldosteronism
Hypersensitivity reactions

The NICE 2019 guidelines states that in patients who are uncontrolled with a SABA (Salbutamol) and ICS (Beclomethasone), LTRA should be added.
If asthma is uncontrolled in adults (aged 17 and over) on a low dose of ICS as maintenance therapy, offer a leukotriene receptor antagonist (LTRA) in addition to the ICS and review the response to treatment in 4 to 8 weeks.