Week 237 - Malabsorption Flashcards
A 30 year old woman presents with an 8 month history of light-headedness and tiredness / fatigue. She c/o pins and needles in her hands and feet, has noted that she’s been a little unsteady on her feet for the past few weeks and mentions that her sore tongue is bothering her. It is red and shiny on examination. What is your top differential and why?
Vitamin B12 deficiency anaemia.
Tiredness and light-headed - signs of anaemia
Parasthaesia in hands and feet - B12 def can cause demyelinating peripheral neuropathy
Red, shiny, painful tongue - suggestive of glossitis 9also caused by Vit B12 def)
List 5 things you would want to illicit from the history of a woman presenting with suspected Vit B12 deficiency aneamia
Diet - vegan / veggie?
FHx of autoimmune disorders (pernicious anaemia)
DHx - methotrexate or Isoniazid
any abdominal Sx e.g. diarrhoea - malabsorption
Abdo surgery - gastrectomy, gastic bypass, terminal ileum
(maybe travel to developing countries)
List 3 specific areas of clinical examination you would want to assess
Signs of anaemia - pallor, tachycardia
Peripheral Neurological - sensation, power, co-ordination
Autoimmune conditions esp. thyroid (goitre)
What skin condition is linked with pernicious anaemia?
Vitiligo (areas of depigmentation)
What is the pathogenesis of pernicious anaemia?
autoantibodies against parietal cells and intrinsic factor
What blood test results might you expect in pernicious anaemia?
Low Hb, high MCV, normal MCH (macrocytic, normochromic anaemia); low serum Vit B12; Low IgA; low serum thyroxine with high TSH maybe
To confirm pernicious anaemia what further blood tests might you request?
Anti-parietal cell and anti-intrinsic factor serology
List 2 medications that you would prescribe to someone with Vit B12 anaemia with low thyroxine and high TSH
Thyroxine and Vit B12 injections
Why would an individual with pernicious anaemia be at increased risk of gastric adenocarcinoma?
Atrophic gastritis is a risk factor - glandular tissues (e.g. those that ordinarily produce intrinsic factor are replaced with intestinal and fibrous tissues
Give another cause of Vit B12 iron deficiency anaemia besides autoimmune
Helicobacter pylori
List blood results that might be typical of a child with Coeliac Disease
Microcytic hypochromic iron deficiency anaemia
Elevated ALT (liver damage common)
High Alk Phos (can be normal or due to osteomalacia)
Low IgA
What might low IgA levels make a child more susceptible to?
Autoimmune conditions
Infection
Asthma and Allergies
What blood test is more specific to Coeliac Disease?
Serum anti-tTG (IgA / IgG)
Once a serum anti-tTG has been performed what is the next most appropriate investigation to do?
jejunal biopsy
Describe the main histological features of Coeliac Disease as seen on a jejunal biopsy
Inflammatory infiltrate Crypt hypoplasia (rather than finger-like projections fairly indistinct block of endothelium)
List 3 differentials that might provide similar histological findings, clinical presentation and lab findings to Coeliac Disease
Post-Viral enteritis
Cow’s milk protein enteropathy
IBD (unlikely in an infant)
What suggestion might you make to help confirm a Coeliac diagnosis that the patient can carry out themselves?
Trial a gluten-free diet - if the symptoms disappear then the diagnosis is confirmed
What is the Coeliac Triad?
> Serum Anti-tTG
Jejunal biopsy
Gluten-free diet
If a child has coeliac what is the likelihood their twin will also develop the condition?
70% chance
What is the risk of a 1st degree relative of a coeliac disease sufferer also developing the condition?
10% chance
What is the risk of a HLA-match relative of a coeliac disease sufferer also developing the condition?
30-40%
What test would indicate it extremely unlikely that a relative of a Coeliac suffer would develop the condition?
if they were found to be HLA DQ2 or DQ8 negative
What is glucose-galactose malabsorption?
A rare autosomal recessive inherited disorder of the SLGT (sodium-coupled glucose-galactose transporter) which results in malabsorption of glucose and galactose and any sugars/CHO that breaks down into either of these.
What are the symptoms of glucose-galactose malabsorption?
Large quantities of watery osmotic diarrhoea (acidic stool); hyperventilation due to metabolic acidosis general malaise in response to glucose or galactose
What is the management for glucose-galactose malabsorption?
A glucose & galactose free diet - Fructose is the only carbohydrate such an individual can have
How do you calculate the ion gap from electrolyte levels and osmoliality of stool sample?
Ion Gap = Osmolality - ([Na+ + K+] x 2)
calculate the ion gap for these stool sample results:
Osmolality = 290 mOsmol/kg
Sodium = 18
Potassium = 62
18 + 62 = 80
80 x 2 = 160
290 - 160 = 130
Describe the pathophysiology of osmotic diarrhoea
When excess osmotically active substances are ingested, pulling excess water into the lumen thus causing large quantities of watery diarrhoea (can also occur with substances poorly absorbed e.g. in food intolerances such as Coeliac Disease or lactose intol.)
What impact will fasting have on osmotic diarrhoea?
Stopping ingestion of the offending agent should stop the diarrhoea
Describe the pathophysiology of secretory diarrhoea
Increase in active secretions into the intestinal lumen or inhibited absorption in response to offending toxin or condition
What impact will fasting have on secretory diarrhoea?
The diarrhoea will most likely continue
Give examples of causes of secretory diarrhoea
(intestinal inflammation) Cholera toxin; IBD; Coeliac Disease Neuroendocrine (NE) tumour Surgical resection Intestinal ischemia Dumping Syndrome
What is Dumping Syndrome?
An iatrogenic syndrome caused by various forms of gastrectomy resulting in profound affects on gastric reservoir, pyloric sphincter mechanism and gastric emptying
Give some examples of causes of Osmotic diarrhoea
Excessive Phosphate, Mg or Sulphate intake (or sodium)
Osmostic laxatives
Sugars or sugar alcohols (Mannitol / Sorbitol)
Lactose intolerance
Maldigestion due to pancreatic disease or Coeliac
Why might steatorrhoea present with bleeding & bone disorders?
Steatorrhoea indicates that fat is not being adequately absorbed > fat soluable Vits are also not (A,D,E,K) > Vit K is responsible for the synthesis of clotting factors II, VII, IX & X; Vit D is responsible for maintaining healthy, bones
What roles does the liver play in digestion?
Digestion: Bile salts (fats > micelles)
Detoxification: chemicals (GIT or systemic blood)
Manufacture: Sugars; Proteins (clotting factors, albumin)
Storage: Glycogen
What roles does the duodenum play in digestion?
Digestion: Chyme and bile; protease, lipase and CHO breakdown (many enzymes)
Absorption: Ca, Mg and Zn
What roles does the jejunum play in digestion?
Absorption: Water and water soluble vitamins; Proteins;
SOME Fat and fat soluble vitamins; Ca, minerals, trace elements; Folate
What roles does the proximal ileum play in digestion?
Absorption: Fat and fat soluble vitamins; Water and water soluble vitamins
What roles does the terminal ileum play in digestion?
Absorption: Vitamin B12; Bile salts; Intrinsic Factor (IF)
What roles does the stomach play in digestion?
Digestion: Parietal cells > HCL, Intrinsic Factor
Chief cells > pepsinogen
Endocrine: G cells > gastrin; D cells > somatostatin
HCO3-
What roles does the pancreas play in digestion?
Digestion: Duct cells > water and bicarbonate
Acinar cells > Pancreatic juices with enzymes
What roles does the colon play in digestion?
Absorbtion: Water
Electrolytes
Short-chain fatty acids (acetate, butyrate, propionate from microbial activity)
