Case 17 Flashcards
What is the MOA of metformin?
Activates AMP dependent protein kinase (hepatically) to reduce gluconeogensis and potentiates effects of endogenously secreted insulin
Why is Metformin first line option?
^Insulin dependent glucose uptake into tissues. Inhibits GI absorption of carbs. Limited ADRs
When is Metformin contraindicated ?
Chronic kidney disease. May provoke lactic acidosis
What is the second line drug for T2D after metformin ?
Gliclazide. Enhances insuline secretion in pancreas
What does Gliclazide act on ?
B cell K ATP effluxes channel to block K efflux. Depolarises B cell –> Ca influx and IP3 mediated enhanced secretion of insulin
Px starts on T2D medication and starts experiencing jaundice, what medication are they on ?
Gliclazide, shows severe hepatic impairment. Normally prior to medication
What is the name of the drug that inhibits breakdown of incretins to 2ndarily enhance insulin secretion from pancreas?
Saxagliptin, often used with metformin or Gliclazide to ^sensitivity to insulin
What is the action of DDP-IV?
Dipeptidyl peptidase IV normally breaks down incretins (GLP-1).
What is Exenatide and how is it administered ?
SC injection. mimics incretin to ^insulin secretion from the pancreas.
How does Exenatide work ?
activates GLP-1 receptors to cause ^insulin secretion. ^insulin sensitivity when used with metformin and Gliclazide
What is Gliflozin ?
SGLT2 inhibitor, ^insulin dependent peripheral glucose uptake and inhibits digestion/absorption of carbs.
What are the superficial causes of T2D ?
Polygenic and environmental risk fx acting together (obesity, lack of exercise, poor diet)
What ethnic groups are more at risk of T2D?
6x more common in south asian
3x if afro-caribbean and African descent
What is the lifelong risk of T2D if one or both parents have the condition ?
One = 40% risk Both = 70% risk
What is the thrifty phenotype ?
Low activity tendencies that store energy, didn’t die in past famines so genes passed on
What is heritability ?
Proportion of observed differences between members of population that are due to genetic influence.
Variance in genotype / variance in phenotype
What is the difference between monozygotic and dizygotic twins ?
MZ share genome
DZ share half
What are the cons to twin studies ?
susceptible to bias (concordant twins ^likely to join) , age at recruitment (may develop at different times) , assumes twins share environmental fx.
What is MODY ? which gene is its most common cause ?
maturity onset diabetes of the young. <25 y/o. no obesity, ketosis, B cell autoimmunity.
HNF1A.
What are neonatal diabetes and mitochondrial diabetes examples of ?
Monogenic diabetes
What is the action of GCK ?
catalyses phosphorylation of glucose and controls rate limiting step of glycolytic pathway
What do mutations of the 7p chromosome cause ?
mild, stable fasting hyperglycaemia (mutated GCK) without complication so no tx required. Px needs to control diet and exercise
What is permanent neonatal diabetes ?
IUGR, sx hyper (<6 months) , ketoacidosis. pancreas insensitive to BG stops producing insulin.
What is the tx for permanent neonatal diabetes ?
Insulin therapy correct hyperglycaemia and results in growth catch up.
What is the non syndromic form of permanent neonatal diabetes ?
mutation in the insulin so still produced but not recognised by receptors.
What is the function of the KCNJ11 and ABCC8 genes ? what happens when they don’t function
Make up the K channel on beta cells allowing binding. If no binding then can’t depolarise so no insulin release.
What is the difference with the syndromic form of neonatal diabetes ?
Shows other associated features.
What is the pathway from the abdominal aorta to the external iliac arteries ?
Abdo –> L/R common iliac arteries -> internal/external iliac.
What is the significance of the inguinal ligament for the femoral artery ?
Below the inguinal ligament = fem artery
Above = external iliac artery.
What is the path of the deep femoral ?
From inguinal ligament beneath satorius muscle gives off deep femoral (thigh) and superficial femoral (below thigh). Deep then branches into medial/lateral circumflex
What structures branch from internal iliac ?
Sup/inf gluteal pass back through greater sciatic foramen (one above and below piriformis muscle).
What is the pathway of the great saphenous vein ?
ankle up medial side to thigh passes through opening in fascia lata (saphenous hiatus) then joins femoral vein.
Describe the path of blood flow after from the femoral vein after the inguinal ligament …
External iliac, joins to internal iliac -> common iliac. R/L common iliac then join at midline –> IVC.
Where do the obturator and femoral nerves arise from ?
anterior rami of 2nd to 5th lumbar nerves and 1st, 2nd, 3rd sacral nerves
What muscles are supplied by the femoral nerve ? (7)
iliac, 4 heads of quads, pectinous, sartorius
What is the path of the obturator nerve ?
emerges below medial border of psoas major. passes through obturator canal just above obturator internus. Emerges over top of obturator externus. Branches run between adductor muscles.
What muscles does the obturator nerve supply ?
Obturator externus, adductor braves and longus, ant part of adductor Magnus
What are the 4 quadricep muscles , where is their origin, what is their function ?
Extend the knee
Vastus intermedius, medialis and lateralis arise from femur
rectus femoris arises from hip bone
what are the hamstring muscles and what is their function ?
knee flexion, hip extension
Semimembranosus, semitendonosus, biceps femoris
What is adductor canal ?
what is it covered by ?
Space between adductor longs and vistas medialis. Femoral vessels run through it from front to back of thigh. Adductor canal is covered by satorius muscle
How are the functions of the hamstrings changed ?
Flexion of knee resisted by quads -> hamstring extends hip.
Extension of hip resisted by hip flexors -> hamstring flexes knee.
What two muscles help the hamstrings to produce flexion? where do they insert ?
Sartorius and gracilis. Insert close to the semitendinosus (medial side of the knee)
What are the muscles in the posterior compartment of the leg ?
Popliteus (medial rotate tibia)
Plantaris (plantarflexion)
Gastrocnemius
What forms the calcaneal tendon ?
‘Achilles’ tendon’. Gastrocneumius joins soleus muscles.
What do the femoral artery and vein become after running beneath the sartorius muscle ?
Emerge at back behind adductor Magnus as popliteal artery and vein.
What are the branches of the popliteal artery ?
Above the knee; two sup genicular arteries (lat/med)
At the knee; two branches to gastrocnemius
Below the knee; two inf genicular arteries (med/lat)
Where does the sciatic nerve divide and what does it divide into ?
Above the knee divides into the tibial and common perineal nerve
What is the path of the tibial nerve, what does it supply ?
Runs down the midline, passes between two heads of gastrocnemius. Supplies popliteus, gastrocnemius and plantaris (post leg)
What muscles perform dorsi and plantar flexion ?
Dorsiflexion, tibialis ant
Plantar, lifts whole body so large muscles ; gastrocnemius, solaris, plantaris
What is the insertion of the Achilles tendon ?
Broad area at the back of the Calcaneus
What are the features of neonatal diabetes ?
IUGR, hyperglycaemia (<1 month) , lack of insulin (resolves after 18 months). Intermittent hypers during intercurrent illness.
What is the structure of K ATP channel ?
made of 4 subunits - Kir6.2
Forms channel pore surrounded by 4 sulfonylurea receptors that reg activity
How do sulfonylureas work ?
Bind to SUR1 receptor (same action as ATP) which closes the channel. K inside the cell^ -> depolarisation which allows insulin to be released.
What is Donohue syndrome ?
Insulin receptor syndrome. ^insulin release from receptor mutations, pre/post natal growth failure.
What distinguishes T2D from MODY ? (4)
polygenic, gene-gene and gene-environment interaction, later onset, pedigree rarely multigenerational
What are the problems with a genetic association study ?
Control and case need to be well matched, multiple testing (eventually scientists found a P value they like) , publication bias
What is epigenetics ?
stable heritable modification of chromosomes without altering DNA sequence through methylation or histone modification -> alters transcriptional potential of genes (silencing)
What was the Barker hypothesis ?
decreased birth and 1 yo weight -> ^risk of IHD.
Poor gestational nutrition leads to what features in later life ? (5)
^CHD, atherogenic lipid profile, poor blood coagulation, ^stress response, ^obesity
What is the difference between rate and ethnicity ?
Race = biological makeup eg. skin colour variation Ethnicity = culture that you associate with
What are the problems with putting people into limited standard categories ?
Groups stable new ones cant emerge, favours dominant groups over diversity.
What are the aims of the ‘together for health diabetes’ delivery plan
Prevention (educate on healthy lifestyle) detection (encourage GPs) Mx (encourage self mx)
What 3 fx influence the age structure of population ?
Fertility, mortality, migration
What is Fries’ compression of morbidity theory ?
Lifespan fixed, chronic disease can be postponed
What are the 4 ‘geriatric giants’ ?
impairment, incontinence, Iatrogenic, instability
Why is the target BP for elderly 140/80 but no lower ?
Increases the risk of postural hypotension
What are the factors of the phenotype model of frailty ?
3/5 required; unintentional weight loss, decreased walking speed, decreased grip strength, subjective exhaustion, decreased physical activity
What indicator of Sarcopenia would be seen on CT ?
Shrinking psoas muscle
What is the contents of the femoral triangle and what structure is the only one palpable ?
Femoral nerve artery and vein. Femoral artery is the only palpable one.
How is the femoral triangle split into fascial compartments ?
Femoral artery and vein then
Femoral nerve and iliopsoas in a different one.
Where would you place the needle for a venous sample in relation to the femoral artery ?
Medially (space)
What are the contents of the femoral canal from lateral to medial ?
femoral nerve , femoral artery , femoral vein, empty space, lymphatics
What is the superior end of the femoral canal bounded by? Why is this structure significant ?
Bounded by femoral ring (just underneath inguinal ligament). Common site of hernias
What is the difference between femoral and indirect inguinal hernias ?
Femoral hernias; below inguinal ligament, medial to femoral artery
Indirect hernias; lateral to the inf epigastric vessels
What is Meralgia Paresthetica?
Lat cutaneous nerve of the thigh passes through inguinal ligament - trapped/compression
Leads to tingling, numbness, burning in lateral thigh
What are the risk fx for Meralgia Paresthetica ?
Tight clothing, obesity, weight gain, pregnancy, diabetic nerve injury
What nerve supplies the posterior lower leg laterally? Common loss of sensation in diabetic neuropathy…
Sural nerve, ‘pins and needles in right lower limb’
What is the blood supply and nerve innervation of the anterior compartment of lower limb ?
Blood supply - anterior tibial artery
Nerve - deep femoral
What compartment of the lower limb is supplied by the fibular artery and innervated by the superior fibular nerve ?
Lateral compartment
How would you differentiate between the lateral and posterior deep sides of lower limb in a cross section ?
Lateral is the fibia side (small bone)
Posterior deep/medial is the tibia (large bone)
What is the blood supply and innervation of the posterior deep and superficial compartments ?
Bloody supply - Posterior tibial artery and fibular artery
Innervation - Tibial nerve
When is a fasciotomy carried out? what is it ?
Bleeding into osteofascial compartment ^pressure as walls are resistant to distension (Ischaemia risk). Incision into leg to relieve pressure/sx.
What are the muscles of the lateral compartment of the leg ? what is their innervation and function ?
Fibularis longus and brevis. Eversion of the foot, innervated by the superficial fibular nerve
What are the risk fx for varicose veins ?
age (peak 50-60) , sex (female - hormone ^during pregnancy) , obesity, occupation, hereditary
What is the most common sight of varicose veins ?
Small saphenous vein (posterior knee)
What arteries can be damaged during proximal femur fractures ? What is their origin ?
Medial and lateral circumflex femoral arteries. Originate from the branches of profunda femoris.
What is plantar tendonitis ?
Persistant pain affecting origin of fascia and surrounding perifascial surfaces. Intense for first few steps of walking then lessens
What does dry gangrene occur ? What provides the supply to the area
Reduced blood supply to the distal regions. Dorsalies pedis (continuation of ant tibial artery)
What is the ABI ? what is the normal range of values ?
Ankle brachial pressure index, ratio of systolic BP in posterior tibial artery to brachial artery. Normal is 0.9 - 1.4
What do high and low ABIs indicate ?
High ABI = calcification/hardening of the vessel
Low ABI = arterial disease (the lower the more severe)