(gastro) disorders of appetite Flashcards
define polydipsia
excessive thirst or excess drinking
define adipsia
inappropriate lack of thirst |(even in severe dehydration)
= with consequent failure to drink in order to correct hyperosmolality
define anorexia
lack or loss of appetite for food
define obesity
abnormal or excessive fat accumulation that presents a risk to health
what types of polydipsic disorders are there?
primary polydipsia = psychogenic and dipsogenic polydipsia
secondary polydipsia
what types of adipsic disorders are there?
four types (A-D)
what are the types of primary polydipsia?
psychogenic = seen in patients with psychiatric disorders
dipsogenic = seen in patients w hypothalamic conditions
differentiate between primary and secondary polydipsia?
primary = a condition where there is excess consumption of fluids leading to polyuria with diluted urine and, ultimately, hyponatremia
secondary = drinking excess water due to disease-induced or medication-induced thirst prompted by an actual need for water
which is the more common type of polydipsia?
secondary polydipsia = more common
(diseases can disrupt the steps of osmoregulation or alter ADH secretion)
what are the causes of secondary polydipsia?
pic
which chronic medical conditions can cause secondary polydipsia?
diabetes insipidus & mellitus
kidney failure
Conn’s syndrome
Addison’s disease
sickle cell anaemia
which medications can cause secondary polydipsia?
diuretics
laxatives
antidepressants
(top two result in dehydration)
which forms of dehydration lead to secondary polydipsia?
acute illness
sweating
fevers
vomiting
diarrhoea
underhydration
what are the most common causes of secondary polydipsia?
diabetes and kidney failure
differentiate between diabetes insipidus and diabetes mellitus
diabete insipidus
- relatively uncommon
- related to pituitary problems
- impaired ADH production
diabetes mellitus
- very common
- related to high blood sugar
compare the treatment for diabetes mellitus to diabetes insipidus
diabetes mellitus = treat the high blood sugar
diabetes insipidus = treat with desmopressin
what causes the large volume of urine in diabetes mellitus?
high sugar levels
= filtered in the kidney and the hypertonic tubular fluid draws more water into the renal filtrate
= forms a higher volume of sugary urine (diuresis)
(higher blood sugar causes diuresis)
why does diabetes mellitus cause polydipsia?
high blood sugar induces diuresis
= higher urine output, more dehydrated and thirstier so you drink more
why does diabetes insipidus cause polydipsia?
pituitary problems (cranial diabetes insipidus, not nephrogenic)
= lack of ADH
= kidney cannot concentrate the urine
= larger amounts of dilute urine are produced
what are the common symptoms of diabetes?
what is Conn’s syndrome alternatively known as?
primary aldosteronism
what is Addison’s disease alternatively known as?
hypoadrenocorticism
how does Conn’s syndrome lead to polydipisia?
dunno whoops
how does Addison’s disease lead to polydipsia?
adrenocortical insufficiency
= less aldosterone produced
= less H2O retention due to less Na+ and Cl- reabsorption
= larger volumes of more dilute urine produced
= increased water loss from the body
= dehydration
= triggers polydipsia
what are the causes of primary polydipsia?
mental illness (psychogenic polydipsia)
- schizophrenia
- mood disorders
- anorexia
- drug use
brain injuries (i.e. to the hypothalamus/pituitary)
organic brain damage
what can polydipsia lead to?
kidney and bone damage
headache
nausea
cramps
low energy, headache
confusion
seizures, slow reflexes
slurred speech
how can polydipsia lead to an electrolyte imbalance?
increased water intake
= reduced osmolality of blood
= hyponatraemia
= can lead to expansion of the cells due to the surrounding water
give examples of mental disorders defined by abnormal eating habits
binge eating disorder
anorexia nervosa
bulimia nervosa
PICA
rumination syndrome
avoidant/restrictive food intake disorder
what is binge eating disorder?
when a person feels compelled to overeat on a regular basis in a short period of time
what is anorexia nervosa?
severe and strong fear of gaining weight
what is bulimia nervosar?
eating large amounts of food and then purging to get rid of extra calories (vomiting/eating laxatives)
what is PICA?
an eating disorder in which a person eats things not usually considered food
what is rumination syndrome?
repeatedly and unintentionally spit up (regurgitate) undigested or partially digested food from the stomach
what is avoidant/restrictive food intake disorder? (ARFID)
extremely picky eaters and have little interest in eating food
what are the signs of anorexia?
low BMI
continuous weight loss
amenorrhea
halitosis
mood swings
dry hair & skin
hair thinning
which hormone is responsible for the mechanism of anorexia?
serotonin (suspected)
how is anorexia classified?
mild: BMI > 17
moderate: BMI of 16–16.99
severe: BMI of 15–15.99
extreme: BMI < 15
what is the threshold for mild anorexia?
BMI > 17
what is the threshold for moderate anorexia?
BMI of 16–16.99
what is the threshold for severe anorexia?
BMI of 15–15.99
what is the threshold for extreme anorexia?
BMI < 15
why is obesity increasing?
(not because physical activity levels are declining)
cheap, calorie-rich/nutrient-poor beverages, sweets and fast food are being increasingly eaten
what is the first step in obesity management?
screen all individuals for being overweight and obesity
what does an obesity/weight management history involve?
assesses for multiple determinants of obesity
- dietary and physical activity patterns
- psychosocial factors
- weight-gaining medications
- familial traits
what is central/abdominal obesity linked to?
increased risk of cardiovascular disease, Alzheimer’s disease, diabetes and asthma
what is BMI?
body mass index
= calculated as weight in kgs/height in square metres
what is BMI measured in?
kg/m^2
what is the BMI threshold that qualifies for treatment?
either BMI of ≥30
or ≥25 + comorbidity or risk factor
which of the following is the most effective treatment of obesity?
a) diet
b) exercise
c) diet + exercise
d) none of the above
pic
when is obesity treated surgically?
in patients EITHER
- with a > BMI 40
OR
- 35+ comorbidities
what are the most common surgical treatments for obesity?
Roux-en-Y gastric bypass
sleeve gastrectomy
what is the function of GLP1 and GLP2?
stimulate insulin release
inhibit glucagon release
what is the function of ghrelin?
‘hunger hormone’
NPY activation - stimulate appetite
what is the function of PYY?
satiety
(anorexigenic = inhibit appetite)
what happens to ghrelin levels after bariatric surgery and why?
ghrelin levels reduce following bariatric surgery
= as ghrelin is mainly produced by the cells of the gastric fundus, which is removed by sleeve gastrectomy (so less ghrelin release)
what happens to GLP1 and GLP2 levels after bariatric surgery and why?
both GLP1 and GLP2 levels increase
= nutrients are absorbed lower down the gut after surgery, and this stimulates more of the GLP1-secreting cells, which are found in higher numbers in the lower gut
what happens to PYY levels after bariatric surgery and why?
PYY levels also increase
(have an appetite inhibiting, and food intake reducing effect)
