Internal Med 8 Flashcards
How do you determine if there is a coexisting metabolic disorder on top of pre-existing anion gap metabolic acidosis
• Determine the difference between calculated anion gap (Na – Cl – HCO3) and normal anion gap (12)
o This is how many extra H+ ions there are
o So you add this number to the measured bicarb to get “corrected” bicarb
o If corrected bicarb is greater than normal bicarb (24), you have a coexisting metabolic alkalosis
o If corrected bicarb is less than normal bicarb (24), you have a coexisting metabolic acidosis
o Example: Na = 140, Cl = 100, Bicarb = 10
♣ Anion gap = 30
♣ Difference between calculated anion gap and normal = 30 – 12 = 18
♣ Add 18 to bicarb to get “corrected” = 10 + 18 = 28
♣ Corrected bicarb is > normal bicarb of 24, so there is a coexisting metabolic alkalosis on top of this metabolic acidosis
Alternative tx of Syphilis if pt is allergic to Penicillin
Doxycycline
What is Whipple disease
♣ Infection with Tropheryma whipplei
♣ Symptoms: Weight loss, lymphadenopathy, hyperpigmentation, cardiac symptoms, arthralgias, neurologic symptoms
♣ Histology: Periodic acid Schiff, PAS (+) foamy macrophages in intestinal lamina propria
What would you expect to see on blood gas of a pt with asthma exacerbation
Respiratory alkalosis due to hyperventilation leading to decreased PaCO2
What would you expect to see in respiratory collapse of a pt with asthma exacerbtion who is unable to meet demands of increased respiratory drive
You will see a normal pH and PaCO2
Inability to maintain adequate ventilation caused by respiratory muscle fatigue or severe air trapping
What abx are used against Anaerobes (think of each category discussed by Jacob)
- Amox/Clav
- Amp/Sul
- Pip/Taxo
- Metronidazole
- Clindamycin
What abx are used against resistant GNR/Pseudomonas
- Pip/Tazo
- Cefepime
- Imipenem
- Meropenem
What abx are used against resistant GPC (MRSA)
- Vancomycin
- Linezolid
- Daptomycin
- TMP/SMX
- Doxy
- Clindamycin
What abd are used against atypicals
- Azithromycin
- Doxy
What is empiric tx of endocarditis
Vancomycin
- It will treat against main culprits: staph, strep, and enterococcus
What drug do you use for Vancomycin-resistant enterococci
Daptomycin
Describe what absorption of D-xylose / urinary excretion indicates
Can be used to assess for Celiac disease
o D-xylose is a monosaccharide that is aborobed in the small intestine without degradation by pancreatic or brush border enzymes
o Patients with small intestinal mucosal disease will have impaired absorption of D-xylose, and thus decreased urinary excretion of D-xylose
o Patients with malabsorption due to enzyme deficiencies (e.g. pancreatitis), will have normal absorption of D-xylose
What is contraction alkalosis?
o Although excess alkali are filtered in the glomerulus, they are also reabsorbed as a result of an activated RAAS
o Hypovolemia triggers RAAS in an attempt to conserve sodium and water
o Aldosteron functions to retain water at the expense of excreting both potassium and acid in the urine, despite total body acid depletion (contraction alkalosis)
How does Lithium cause nephrogenic DI
Lithium antagonizes the action of ADH in the collecting tubules, which means that aquaporins don’t get put into the collecting duct
How do you treat nephrogenic DI secondary to Lithium
Amiloride
• Lithium enters the convoluted tubule via the ENac channel, so inhibiting this channel will inhibit lithium entering, so Lithium can no longer antagonize the effect of ADH
What will you see in the setting of abrupt withdrawal of exogenous steroids in:
- Cortisol
- ACTH
- Aldosterone
This is tertiary adrenal insufficiency (problem of the hypothalamus)
- Low cortisol
- *Low ACTH
- Normal Aldo (controlled by RAAS)
Describe cause of common variable immunodeficiency (CVID)
o Defect in B-cell differentiation
♣ B cell count is normal
♣ Plasma cells and all immunoglobulins are decreased
Manifestations of CVID
♣ Recurrent respiratory (e.g. pneumonia, sinusitis, otitis) and GI (e.g. Salmonella, Campylobacter) infections
♣ Autoimmune disease (e.g. RA, thyroid disease)
♣ Chronic lung disease (e.g. bronchiectasis)
♣ GI disorders (e.g. chronic diarrhea, IBD-like conditions)
Tx of CVID
♣ Immunoglobulin replacement therapy
Describe the autoimmune target/histology in Pemphigus Vulgaris vs. Bullous Pemphigoid
Pemphigus vulgaris
- Autoimmune destruction of desmosomes (connection between cells of the stratum spinosum)
• Basal layer remains attached “tombstone” appearance
• Immunofluorescence will have a fish net appearance IgG and C3 deposits in a “chicken wire” pattern
Bullous Pemphigoid
♣ Autoimmune (IgG) destruction of hemidesmosomes (connection between basal cell layer and basement membrane)
• Basal layer detached from basement membrane
• Immunofluorescence will be in a linear pattern IgG along basement membrane
Describe clinical presentation of Pemphigus Vulgaris vs. Bullous Pemphigoid
Pemphigus Vulgaris
• Flaccid bullae and ulcers
• (+) Nikolsky sign (separation of epidermis upon manual stroking of skin) thin-walled bullae that rupture easily
• Oral mucosa involved
Bullous pemphigoid
♣ Tense bullae do not rupture easily (- Nikolsky sign)
♣ Oral mucosa NOT involved
Empiric tx of outpatient CAP
o Macrolide (e.g. Azithromycin) or doxycycline (healthy) o Fluoroquinolone or beta-lactam + macrolide (comorbidities)
Empiric tx of inpatient non-ICU CAP
o Fluoroquinolone (IV) – respiratory fluoroquinolones = Levofloxacin, Moxifloxacin o Beta-lactam (e.g. Ceftriaxone) + macrolide (IV)
Empiric tx of inpatient ICU CAP
o Beta-lactam + macrolide (IV)
o Beta-lactam + fluoroquinoloe (IV)
What lab value can differentiate between folate and B12 deficiency
Methylmalonic acid
Will be high in B12 deficiency and nl in folate def
Causes of B12 deficiency
- Strict long-term veganism
- Pernicious anemia
- Crohn’s
- Pancreatic insufficiency
- Gastric bypass
Describe how pernicious anemia causes B12 deficiency
o B12 deficiency due to autoimmune destruction of gastric mucosa (parietal cells in the stomach), which leads to IF deficiency
♣ Recall that parietal cells produce intrinsic factor, which is necessary for B12 absorption
How does Crohn’s cause B12 deficiency
o Damage to terminal ileum (e.g. Crohn’s) site of absorption
Describe how you find out if B12 deficiency is due to poor nutrition or due to malabsorption
Schilling test = Determines if cause of B12 deficiency is due to poor nutrition or poor absorption
o Give pt IM injection of B12 to saturate liver
o Then give pt oral B12 and check urine
o Because body is saturated, all oral B12 will be absorbed and then excreted in the urine, so pt will have positive B12 in urine IF they were able to absorb it
♣ = deficiency due to poor nutrition
o If urine is negative for B12, that means there was poor absorption
♣ = deficiency due to malabsorption
Causes of non-megaloblastic macrocytic anemai
- Liver disease
- Alcohol
- Drugs (e.g. 5-fluorouracil, Zidovudine)
- Metabolic (e.g. hereditary orotic aciduria)
What will you see with the following in iron deficiency anemia:
- Ferritin
- Iron
- %Sat
- TIBC
• Low ferritin (low iron stores)
• Low serum iron
• Low % saturation (of transferrin – iron transporter)
High TIBC
What will you see with the following in anemia of chronic disease:
- Ferritin
- Iron
- %Sat
- TIBC
- High ferritin
- Low TIBC
- Low serum iron
- Low % saturation
What lab values can you use to evaluate for hemolysis vs. hemorrhage in anemia
In hemolysis you will see:
o Elevated LDH
o Low Haptoglobin
o Elevated T. Bili / D. Bili
Tx of sickle cell
♣ Hydroxyurea – increases production of HbF
Osmotic fragility test is positive in what disease?
♣ Osmotic fragility test – High percentage of lysis of RBCs in hypotonic solution
Tx of osmotic fragility test
Splenectomy
Coombs test will be positive in what anemia
Autoimmune hemolytic anemia
What are the two types of autoimmune hemolytic anemia and how do you differentiate?
Warm = IgG antibodies Cold = IgM antibodies
Describe cause of paroxysmal nocturnal hemoglobinuria
o Deficiency of GPI, which usually anchors DAF (CD55) to RBC membrane to protect from complement destruction
♣ Complement is activated in acidic situations
♣ Lysis occurs at night due mild respiratory acidosis
What are the effects of ACEi on potassium
Lead to hyperkalemia due to decreased aldosterone levels
Tx of sciatica
Usually has spontaneous resolution so initial management is relief of sx = NSAIDs and Acetaminophen
What should you test for in a pt with pseudogout and hepatomegaly
Hemochromatosis (iron studies)
What is hemochromatosis
o Excess iron
♣ Recessive mutation in HFE gene = abnormal iron sensing = increased intestinal absorption
Presentation of hemochromatsosis
♣ Liver = elevated hepatic enzymes with hepatomegaly (early), cirrhosis (later), and increased risk of hepatocellular carcinoma
♣ Pancreas = DM
♣ Skin = bronze (due to hemosiderin deposition in macrophages)
♣ MSK = arthralgia, arthropathy, and chondrocalcinosis (pseudogout)
♣ Heart = arrhythmias; dilated cardiomyopathy
♣ Testes = atrophied
Tx of aortic dissection
♣ Pain control (e.g. Morphine)
♣ IV beta blockers (ot decreased LV contractility)
♣ +/- Sodium nitroprusside (if SBP >120)
♣ Urgent surgical repair for ascending dissection
Diagnose: Periodic back pain radiating to buttocks and thighs
Lumbar spinal stenosis
Diagnose: Acute back pain with unilateral radiation down sciatic nerve to foot
Lumbar disc herniation
