Weight gain Flashcards
Causes of weight gain - non-pathological increased lean mass
- exercise
- growth
- pregnancy
Causes of weight gain - pathological increased lean mass
- neoplasia
- hyperplasia
- inflammation
- cysts/abscesses
- organomegaly -> disease/iatrogenic (e.g. Cushing’s/GCs)
- fluid retention
– hypovolaemia
– oedema
– 3rd spacing (e.g. ascites, pleural effusion, pericardial effusion)
Weight gain - common obesity causes
Non-pathological:
- over feeding
- reduced exercise (possible pathology)
- predispositions (age, neutering, breed, O)
Increased appetite
- systemic dz with normal caloric demand e.g. Cushing’s
- systemic dz with higher caloric demand e.g. acromegaly, insulinoma
- iatrogenic e.g. glucocorticoids, phenobarbitone, mirtazapine
- behavioural/psychological/neurological
Normal appetite but decreased metabolic rate
- hypothyroidism
Acromegaly - what is it? pathophysiology?
= increased growth hormone
Cats
- usually associated with functional pituitary adenoma
- mostly males middle age/older
Dogs
- usually unneutered females
- due to elevated progesterone levels in the luteal phase or exogenous progesterone admin (iatrogenic)
Acromegaly - CS
Increased risk of DM due to insulin resistance
- polyuria
- polydipsia
- polyphagia
BUT weight gain instead of weight loss
Cutaneous thickening, macroglossia, increased dental spacing, prognathism
Acromegaly - diagnosis
CS + elevated serum GH and IGF-1 (early insulin therapy can cause false negatives)
Acromegaly - tx options
Surgery
- tx of choice
- dogs: OVH and mammary strip
- cats: hypophysectomy but expensive and invasive
Radiotherapy
Drugs
- e.g. somatostatin analogues, dopaminergic agonists (e.g. cabergoline) and GH receptor antagonists
Insulinomas - pathophysiology
Functional neuroendocrine tumour of the pancreas
- beta cells of islets of Langerhans
- secrets multiple hormones including somatostatin, glucagon, gastrin, pancreatic polypeptide, IGF1 and serotonin and insulin
- excessive insulin -> low BG -> CS
- mostly malignant
Insulinomas - signalment
- uncommon in dogs, rare in cats
- any gender, more common in large breeds
Insulinomas - CS
- increased appetite and weight gain (BCS)
- weakness, ataxia, collapse, seizures
– particularly after exercise/fasting or feeding (stimulates insulin release)
– glucose admin improves signs
Insulinomas - diagnosis with bloods
Demonstrate hypoglycaemia (BG <3mmol/l) while CS, which resolve with glucose admin
Hx, CE & routine blood
- exclude other causes of hypoglycaemia e.g. sepsis, liver failure, Addison’s, toxin ingestion etc)
Increased suspicion if
- increased insulin:glucose (not sent or spec)
- low fructosamine
Insulinomas - diagnosis with imaging
US & x-ray chest and abdomen
- looking for mass or mets
- 50-75% insulinomas visible on US
Dual-phase CT angiography may be the best but still can miss some
Insulinomas - diagnosis for small lesions
- for small lesions ex-lap may be required for diagnosis and tx
Insulinomas - surgery
Excisional biopsy tx of choice
Even with mets can reduce CS
- care to correct BG before/during GA
- nodulectomy or partial pancreatectomy
- possible post-op complications
– pancreatitis, persistent hypoglycaemia (incomplete removal/mets), DM, hyperglycaemia (beta-cell atrophy)
Insulinomas - medical management
If surgery not feasible / recurrence / persistent hypoglycaemia
Diet
- multiple small meals high in protein, fat and complex carbs
Preds
- 0.25mg/kg BIG
- insulin antagnost and stimulates glucose-genesis and glycogenolysis
Octreotide
- inhibits insulin synthesis and secretion
Diazoxide
- 5-10mg/kg BID
- stimulates gluconeogenesis and glycogenolysis, decreasing insulin release
Insulinomas - chemotherapy
Streptozotocin
- adjunctive chemo agents
- cytotoxic to pancreatic beta cells
- caution as nephrotoxic and can cause DM
Insulinomas - staging
Stage I: only pancreas affected
Stage II: regional LN mets
Stage II: distant mets
Insulinomas - prognosis / median survival
Stage I: with surgical excision >2y
Stage II or III: approx 6m regardless of tx
