Endocrine Flashcards
What is the primary source of endogenous glucose production?
Liver
What does a normal glucose level require?
a balance b/w glucose usage and endogenous production or dietary carbohydrate intake
How does the liver alter glucose levels/ in what ways?
glycogenolysis and gluconeogenesis
What percentage of glucose release by the liver is metabolized by insulin-insensitive tissues?
70-80%
What are examples of insulin-insensitive tissues?
Brain, GI tract, red blood cells!
When does the transition from exogenous usage to endogenous production of glucose occur to maintain a normal glucose level?
2-4 hours after eating, happens when glucose usage exceeds production (ex: doing squats to build that ass)
What is fundamental for the maintenance of normal blood glucose 2-4 hours after eating?
diminished insulin production is fundamental! Don’t wanna completely tank
What hormones comprise the glucose counter-regulatory system and support glucose production?
glucagon, epinephrine, growth hormone, and cortisol
Tell me about the role of glucagon
glucagon plays a primary role by stimulating glycogenolysis and gluconeogenesis, and inhibits glycolysis
What is the MOST COMMON endocrine disease?
Diabetes Mellitus, affects 1 in 10 adults
What does Diabetes Mellitus result from?
-an inadequate supply of insulin and or an inadequate tissue response to insulin
-leads to increased circulating glucose levels with eventual microvascular and macrovascular complications
What is type 1a diabetes caused by?
T-cell-mediated autoimmune destruction of Beta cells within pancreatic islets, leading to minimal or absent circulating insulin levels
Tell me about type 1b diabetes.
It’s a rare disease of absolute insulin deficiency, which is not immune mediated
Is type 2 diabetes immune mediated?
Nope, results from defects in insulin receptors and post-receptor intracellular signaling pathways
Facts about type 1 DM:
-accounts for 5-10% of all DM
-usually diagnosed before age 40
-the exact autoimmune cause is unknown
-involves a long preclinical period (9-13 years) of b-cell antigen production that precedes the onset of symptoms
-80-90% of B cell function is lost before hyperglycemia ensues
What is hyperglycemia over several days/ weeks associated with? (S/S)
-fatigue, weight loss, polyuria, polydipsia, blurry vision, hypovolemia, ketoacidosis
-Dr. Mordecai’s friends realized their daughter had type 1 b/c she started peeing the bed randomly at 11 years old
Facts about Type 2 DM:
-increasingly seen in younger patients and children over the past decade
-very under-diagnosed, normally present 4-7 years before diagnosed
-with disease progression, pancreatic function decreases and insulin levels become inadequate
3 main abnormalities seen in DM Type 2:
-increased hepatic glucose release caused by a reduction in insulin’s inhibitory effect on the liver
-impaired insulin secretion
-insufficient glucose uptake in peripheral tissues
What is type 2 DM characterized by?
insulin resistance:( in skeletal muscle, adipose and liver
What are some causes of insulin resistance?
-abnormal insulin molecules
-circulating insulin antagonist
-insulin receptor defects
What are acquired/ contributing factors to DM type 2?
obesity and sedentary lifestyle
How is Diabetes diagnosed?
fasting blood glucose and HbA1C
What are normal, pre-diabetic, and diabetic A1C percentages?
-normal: <5.7%
-pre-diabetic: 5.7-6.4%
-diabetic: >6.5%
Info on the American Diabetes Association for the Diagnosis of Diabetes chart:
- A1c >6.5%. The test should be performed in a lab using a method that is NGSP certified
- Fasting blood glucose >126 mg/dL (7 mmol) fasting is defined by no calorie intake for at least 8 hr
- 2 hour plasma glucose >200 mg/dL (11.1 mmol) during an OGTT-test should be performed using glucose load equivalent to 75 g glucose
- class s/s of hyperglycemia or hyperglycemic crisis, a random plasma glucose >200 mg/dL
What are the first things you do to treat type 2 diabetes?
-dietary adjustments and exercise/weight loss
-decreasing body fat improves hepatic and peripheral insulin sensitivity
Tell me about Metformin.
-the preferred initial drug treatment!
-biguanide
-enhances glucose transport into tissues
-decreased triglycerides and LDL levels
what do Sulfonylureas do?
-stimulate insulin secretion
-enhances glucose transport into tissues
Are Sulfonylureas good long term treatment for DM?
Nope! d/t diabetic progressive loss of B cell function
Side effects of Sulfonylureas:
hypoglycemia, weight gain, and cardiac effects :(
How much can lifestyle changes like weight loss and exercise drop A1c?
-1-2 points
-insufficient for most within first year owing to inadequate weight loss and weight gain
How much can metformin drop A1c?
-1-2 points
-weight neutral
-GI side effects, contraindicated with renal insufficiency (GFR<30 mL/min)
How much can insulin drop A1c levels?
-1.5-3.5 points
-no dose limit, rapidly effective, improved lipid profile
-1-4 injections daily (monitor for weight gain and hypoglycemia)
How much can sulfonylureas drop A1c?
-1-2 points
-rapidly effective but can cause weight gain and hypoglycemia, especially with glibenclamide or chlorpropamide
How much can GLP1 receptor agonists drop A1c?
-0.5-1.5 points
-requires injection and has frequent GI side effects
What are the positive effects of GLP1 agonists?
weight loss, reduction in major adverse cardiovascular events (liraglutide, semaglutide, dulaglutide) in patients with established CVD and potentially those with high risk CVD
How much is insulin required for type 1 and type 2 diabetes?
needed in ALL type 1 cases and 30% of type 2 cases
What kind of insulin do we give in the OR?
short-acting (regular)
What type of insulin is NPH/Lente?
basal/intermediate-acting
What is the most dangerous complication to long-acting insulin (ultralente, glargine)
hypoglycemia-exacerbated by ETOH, metformin, sulfonylureas, ACE-I’s, MAOI’s, non-selective beta blockers
What can repetitive hypoglycemic episodes lead to?
hypoglycemia unawareness
What is hypoglycemia unawareness?
patient becomes desensitized to hypoglycemia and doesn’t show autonomic symptoms (so patient can’t sense drop in blood sugars)
Hypoglycemia unawareness leads to neuroglycopenia. What does this include? How is it treated?
-fatigue, confusion, headache, seizures, coma
-treatment: po or IV glucose (may give SQ or Im if unconscious)
Here’s a pic of a graph showing that rapid insulin lasts the shortest amount of time and long acting lasts the longest:)
-rapid: aspart, lispro, glulisine, inhaled human insulin
-short: regular U-100
-intermediate: NPH
-long: detemir
-long: U-100 glargine
-ultra-long: glargine U-300
-ultra-long: degludec
Lispro (Humalog) and Aspart (Novolog) onset, peak, and duration:
onset: 10-15 minutes
peak: 1-2 hours
duration: 3-6 hours
Human regular insulin onset, peak, and duration:
onset: 30 minutes
peak: 2-4 hours
duration: 5-8 hours
Human NPH and Lente insulin onset, peak, and duration:
onset: 1-2 hours
peak: 6-10 hours
duration: 10-20 hours
Glargine (Lantus) insulin onset, peak, and duration:
onset: 1-2 hours
peak: n/a
duration: 24 hours
Ultralente insulin onset, peak, and duration:
onset: 4-6 hours
peak: 8-20 hours
duration: 24-48 hours
What is a complication of DM?
DKA :( mortality is 1-2%
Which type of DM is DKA more common with?
type 1-often triggered by infection/illness
What does the high glucose exceeding threshold for renal reabsorption that happens with DKA cause?
It causes osmotic diuresis and hypovolemia
What does tight metabolic coupling of gluconeogenesis and ketogenesis lead to in DKA?
leads to liver overproduction of ketoacidosis
What does DKA result in?
excessive glucose-counterregulatory hormones with glucagon activating lipless and free fatty acids-substrates for ketogenesis
Diagnostic features of DKA:
-serum glucose: > or equal to 300 mg/dL
-pH: < or equal to 7.3
-HCO3: < or equal to18 mEq/L
-serum osmolarity: <320 mOsm/L
-serum and urine ketone levels: moderate to high
DKA Treatment:
-IV volume replacement
-insulin: loading dose 0.1 mcg regular + low dose infusion @ 0.1 mcg/kg/hr
-correct acidosis w/ sodium bicarb
-electrolyte supplement: K+, phosphate, magnesium, and sodium
-correction of glucose w/o simultaneous correction of sodium may result in cerebral edema
What does HHS stand for?
Hyperglycemic Hyperosmolar Syndrome
What is HHS characterized by?
-severe hyperglycemia, hyperosmolarity, and dehydration
With what type of DM does HHS normally occur and at what age?
-type 2 DM and over 60 years old
Is HHS immediate?
No, it evolves over days to weeks with persistent glycosuric diuresis
What happens in HHS when glucose load exceeds max renal glucose absorption?
Mass solute diuresis occurs
What are the symptoms of HHS?
-polyuria, polydipsia, hypovolemia, hypotension, tachycardia, and organ hypoperfusion
What can hyperosmolarity lead to?
coma :(
With HHS and DKA, which is more likely to have acidosis?
DKA! HHS can have some degree of acidosis but not as much as DKA can.
What is the treatment for HHS?
-fluid resuscitation, insulin bolus + infusion, electrolytes
-mortality rate is 10-20% (much higher than DKA)
What do microvascular complications of DM refer to?
non-occlusive microcirculatory disease with impaired blood flow autoregulation
What is the Diabetic Nephropathy?
-30-40% of DMI and 5-10% DMII develop ESRD
-Kidneys develop glomerulosclerosis, arteriosclerosis, and tubulointerstitial disease
Symptoms of Nephropathy:
HTN, proteinuria, peripheral edema, and decreased GFR
What happens in reference to electrolytes when GFR drops lower than 15-20 mL/min?
The kidneys can no longer clear potassium and the patient becomes hyperkalemic and acidotic
How can ACE-I’s help fight against nephropathy?
They slow the progression of proteinuria and the rate of GFR slowing
What is involved in the treatment of ESSRD?
hemodialysis and peritoneal dialysis, and kidney transplant
What is something that can prevent recurrent nephropathy?
If you’re gonna get a kidney transplant, go ahead and get a new pancreas too-better outcomes than just kidney transplant
Tell me about peripheral neuropathy
-It’s normally a distal, symmetric diffuse sensorimotor polyneuropathy that starts in the toes/feet and progresses proximally
-involves loss of large sensory motor fibers which reduces light touch and proprioception
-also lose small nerve fibers which means decreased pain/temperature perception causing neuropathic pain
What can peripheral neuropathy lead to?
-ulcers b/c mechanical and traumatic injury goes unnoticed:(
(this is why always wears boots lol)
-significant morbidity results from recurrent infections and amputation wounds
What is the treatment for peripheral neuropathy?
-Optimal glucose control
-NSAIDS
-Antidepressants
-Anticonvulsants
What is diabetic retinopathy?
It’s caused by microvascular changes including vessel occlusion, dilation, increased permeability, and micro aneurysms
-visual impairment ranges from color loss to blindness
-glycemic control and BP control reduces the progression
What is autonomic Neuropathy?
It can affect any part of ANS and is caused by damaged vasoconstrictor fibers, impaired baroreceptors, and ineffective cardiovascular activity
What are the CV symptoms of autonomic neuropathy?
abnormal HR control and vascular dynamics, resting tachycardia, loss of HR variability, progresses to orthostatic hypotension and dysrhythmias
What are the GI symptoms of autonomic neuropathy?
-decreased gastric secretions and motility, eventually causing gastroparesis
-N/V, early satiety, bloating, and epigastric pain
What is the treatment for autonomic neuropathy?
glucose control, small meals, and prokinetics
What to include in preop eval for DM patients:
-emphasize CV, renal, neuro, and MDK systems and remember that silent ischemia is possible with autonomic neuropathy
-consider stress test in pts w/ multiple cardiac risk factors and poor exercise tolerance
-pay close attention to hydration status, avoid nephrotoxins, and preserve renal blood flow
What does autonomic neuropathy predispose patient to?
peri-operative dysrhythmia and hypotension
What does gastroparesis increase your risk for?
Aspiration, REGARDLESS of NPO status
What meds should you hold when it comes to DM patients?
Hold p.o. hypoglycemic and non-insulin injectable drugs should be held the morning of surgery
What is Insulinoma?
It’s a rare, benign insulin-secreting pancreatic islet tumor that occurs 2x more in females than males, normally b/w 50-60 years old
What is Whipple’s triad, which is used to diagnose Insulinoma?
- Hypoglycemia with fasting
- Glucose <50 with symptoms
- Symptoms relief with glucose
diagnosis based on inappropriately high insulin level during 48-72 hour fast
What to do for Insulinoma patients preop:
-Diazoxide which inhibits insulin release from B cells
-Other treatment: verapamil, phenytoin, propranolol, glucocorticoids, and octreotide
True or false: surgery is curative for Inulinoma?
TRUE!
What is important to consider intra-op for patients with Insulinoma?
Hypoglycemia can occur intra-op followed by hyperglycemia once the tumor is removed. Tight glycemic control is paramount!
Per Dr. Mordecai, the pt will probably be on an insulin get post-op
How much does the thyroid gland weigh and what are the two lobes joined together by?
20 grams, 2 lobes are joined together by an isthmus
What is the thyroid gland affixed to?Just
the anterior and lateral trachea, with upper border just below the cricoid cartilage
Where are the parathyroid glands located?
On the posterior aspects of each thyroid lobe
What is the rich capillary network that permeates the thyroid gland innervated by?
The adrenergic and cholinergic nervous systems
What nerves are in close proximity to the thyroid?
The recurrent laryngeal nerve and external motor branch of superior laryngeal nerve
The thyroid is composed of follicles. What are they filled with?
Thyroglobulin, an iodinated glycoprotein and substrate for thyroid hormone synthesis
What are the specific cells in the thyroid that produce calcitonin?
Parafollicular cells!
What does production of normal quantities of thyroid hormone depend on?
The availability of exogenous iodine
What is the primary source of iodine?
Our diet!
What is iodine reduced to in the GI tract?
Iodide-after reduction it is rapidly absorbed into the blood and then transported into thyroid follicular cells
What is the binding of iodide to thyroglobulin catalyzed by? What does this yield?
an iodinate enzyme and yields inactive monoiodotyrosine and diiodotyrosine
What percentage of monoiodotyrosine and diiodotyrosine undergoes coupling with thyroid peroxidase? What does this form?
25%, forms active triiodothyronine (T3) and Thyroxine (T4)
True or false: the thyroid has a large store of hormones and has a low turnover rate?
True!
This allows protection against depletion if hormone synthesis is impaired.
What is the T4/T3 ratio?
10:1 (so more T4 than T3)
T4 and T3 reversibly bound to these three major proteins:
TBG or thyroxine-binding globulin (80%), pre albumin (10-15%) and albumin (5-10%)
What metabolic processes does thyroid hormone stimulate?
Virtually all of them!
They influence growth and maturation of tissues, enhance tissue function, and stimulate protein synthesis and carbohydrate and fat metabolism
What are the controllers of regulation of thyroid function?
Hypothalamus, pituitary gland, and thyroid glands-in a classic feedback control system
So thyroid has an auto regulatory mechanism that maintains consistent hormone stores!