Disorders of Appetite Flashcards
What is water intake VS food intake regulated?
Water intake = thirst
Food intake = appetite
Define the terms:
Polydipsia
Adipsia
Anorexia
Obesity
Polydipsia = excessive thirst or excess drinking
Adipsia = inappropriate lack of thirst with consequent failure to drink in order to correct hyperosmolality
Anorexia = lack or loss of appetite for food
Obesity = abnormal or excessive fat accumulation that presents a risk to health
What is the difference between Anorexia VS Anorexia Nervosa?
Anorexia = medical symptoms for lack / loss of appetite for food
Anorexia nervosa = psychological eating disorder
What are the 2 types of thirst disorders?
Polydipsic = drinking too much
OR
Adipsic = drinking too little
What are the 2 types of polydipsic disorders?
Primary
Secondary - more common
What are the 2 types of adipsic disorders?
Primary
Secondary
What is secondary polydipsia?
Secondary = result of anotehr ongoing condition
e.g. medical issues / medications that disrupt any step in osmoregulation or alter ADH production / release
What are the possible causes of secondary polydipsia?
Chronic medical conditions = Diabetes insipidus & mellitus Kidney failure Conn’s syndrome (primary aldosteronism) Addison's disease (hypoadrenocorticsm) Sickle cell anaemia
Medications =
Diuretics
Laxatives
Antidepressants
Dehydration = Acute illness Sweating Fevers Vomiting Diarrhoea Underhydration
What does insipid mean?
What does mellitus mean?
Tasteless
Sweet tasting / ‘honeyed’ (sweet urine)
How do diabetes mellitus (DM) and diabetes insipidus (DI) differ?
Both lead to large volumes of urine
DM =
General population - common
Related to high blood sugar - high BGL filtered in the kidneys = draws more water out of the nephrons along with it = higher volume of sugary urine
High BGL induces this diuresis
Treatment of high blood sugar = control of blood sugar to stop patients passing high volumes of sweet urine
DI =
General population - uncommon
Related to pituitary problems = lack of ADH release from posterior pituitary (condition may be called cranial diabetes)
Impaired ADH production means kidneys cannot concentrate the urine
Treatment with desmopressin - synthetic long acting form of ADH
48M - Mr Smith
Unhealed wound on shin
Lost some weight
Frequently goes to the toilet (interrupts his meetings)
Relationhip w/ wife is not what it used to be
What is wrong with Mr Smith
Diabetes Mellitus
What are the key signs and symptoms of diabetes mellitus?
Always being tired Frequent urination Sudden weightloss Unhealed wounds Sexual problems Always hungry Blurry vision Numb or tingling hands / feet Always thirsty Opportunistic infections e.g. vaginal infections
What are some other medical conditions that can lead to polydipsia?
Acute kidney failure - toxins, trauma, systemic infections, cancer, urinary obstruction, heatstroke
Conn’s syndrome - primary aldosteronism (overproduction of aldosterone = increased Na+ and K+ in the blood)
Addison’s disease - hypoadrenocorticism (adrenal cortical insufficiency) = inability to concentrate urine despite normal renal function
What causes primary polydipsia?
Psychogenic polydipsia (or acquired)
Schizophrenia (20% with chornic SZ = psychogenic polydipsia)
Mood disorders e.g. depression and anxiety
Anorexia
Drug use
Brain injuries -
Organic brain damage - e.g. myelination syndromes, motor neuron disease etc.
84F -
Multiple coronary angioplasties
Used to enjoy walks - now severe shortness of breath walking around the house
Dr prescribed some medications for this
Forgetful, finds it difficult to answer granddaughters texts
Polydipsia
Dry lips
Why does Mrs Smith drink do much water and why are her lips dry?
Accumulation of water secondary to her heart failure
This is treated by thiazides - prescribed by her doctor (this is a diuretic)
So the diuretics are causing her symptoms
Why is polydipsia a problem?
Upset electrolyte balance in the body = diluted blood = hypernatremia = swelling Kidney and bone damage Headache Nausea Cramps Slow reflexes Slurred speech Low energy Confusion Seizures
What are the 4 types of adipsia?
Adipsia may also be called hypodipsia
Type A - most common (AKA essential hyponatremia) - increased osmotic threshold = molecules cannot pass through the membranes
Type B - decreased ADH response even if there is an osmotic stimuli, likely to be due to elimination of osmoreceptors
Type C - completely eliminated osmoreceptors
Type D - ADH release occurs with normally functioning levels of osmoregulation
What is the mechanism of the lack of thirst sensation in adipsia?
Increased osmolality of urine stimulates ADH secretion
Leads to water retention and sensation of thirst decreases
V. rare disorder - lack of research
How do the osmoreceptors detect plasma osmolarity and how does it affect ADH release?
Cells shrink when plasma becomes more concentrated
Proportion of cation channels increase - membrane depolarises
Sends signals (increases neuronal firing frequencies) to the ADH producing cells to increase ADH production
Leads to fluid retention and invokes thirst / drinking
What are eating disorders?
Thought to be low food intake previously
Definition now currently stands at range of psychological conditions caused by unhealthy eating habits e.g. obsession with body weight, binge eating, etc.
Can cause serious health issues
What are some examples for eating disorders?
Binge eating disorder - high body weight
Anorexia nervosa - eat little due to fear of gaining weight
Bulimia nervosa - people eat a lot then try to get rid of it (e.g. via laxatives, throwing up)
Pica - eating non-food items (i.e. things with no nutritional value)
Rumination syndrome - regurgitate food and swallow
Avoidant/restrictive food intake disorder - reduced / selected food intake (narrow spectrum of food in the diet) but not driven by fear of gaining weight
What is the global prevalence of eating disorders?
Global eating disorder prevalence increased from 3.4% to 7.8% between 2000 and 2018
70 million people live with eating disorder
What are the signs of anorexia?
Signs and symptoms are due to lack of nutrients - Low BMI Continuous weight loss Amenorrhea Halitosis Mood swings Dry hair, skin and hair thin
What are the different BMI categories for anorexia?
Mild: BMI > 17
Moderate: BMI of 16–16.99
Severe: BMI of 15–15.99
Extreme: BMI < 15
What are the causes and mechanism of anorexia?
Genetic predisposition, environmental, psychological, sociological
Mechanism via serotonin
Normal hormonal response to challenges with serotonergic agents
Increased CSF conc of serotonin and metabolites of serotonin are found in the urine and blood
What is halitosis?
Bad breath
15F - Miss Smith
Lives with her parents
Tired and abnormally thin
Gingival bleed (bleeding in the mouth from the gums)
Wanted to see her dentist - but parents didn’t let her
Under pressure at school, but enjoys meeting her friends
Can’t wait til the end of lockdown
Often feels hungry, would like to eat more
Why has Miss Smith got gingival bleeding and why has she lost weight?
Child neglect - scurvy
What percentage of the worlds population will be obese by 2030?
51%
Why is obesity increasing?
Cheap, calorie rich, readily available food
Not lack of exercise necessarily - as physical activity declines prior to obesity epidemic
What are the screening tools used for obesity?
Height, weight and abdominal girth
Medical history: dietary and physical activity patterns, psychosocial factors, weight-gaining medications, familial traits
BMI = kg/m2
BMI of ≥30 or ≥25 + comorbidity or risk factor = considered for treatment
What are the 2 types of obesity?
Central obesity - strongly linked to CVD, DM, Alzheimers
General obesity
What are the treatment options for obesity?
Life style modification = diet, exercise
Pharmacological treatments
Surgical treatments
What surgical treatments are available for obesity?
People with a > BMI 40 or 35+ comorbidities
Various procedures: bariatric or metabolic surgery = minimally invasive, various types are absorptive (stops food being absorbed) or restrictive (stops patient from being able to put in a lot of food for it to be absorbed)
Most common Roux-en-Y gastric bypass & sleeve gastrectomy
WL 5 yrs after BS: 30% - 35%
Remission of comorbidities =
Diabetes (80%)
OSA (80%-85%)
What are the hormones related to obesity?
GLP1 and GLP2:
Stimulate insulin release
Inhibit glucagon release
Ghrelin:
Hunger hormone
NPY activation – initiate appetite
PYY:
Satiety
Anorexogenic
What hormonal changes are seen after bariatric surgery?
Ghrelin reduces
GLP1, GLP2 and PYY elevated
