Chemistry Flashcards
What is the function of cystatin C
Measure GFR
*Endogenous substances used to determine GFR are urea nitrogen, creatinine and cystatin C
Pt has low serum cholinesterase level–what is next step in workup?
Test if cholinesterase can be inhibited by dubicaine
**In hereditary hypocholinesterasemia, cholinesterase will not be inhibited by dubicaine
Most common drug to cause drug-induced lupus?
procainamide
Which lipid tests are invalid if patient is not fasting?
triglycerides and calculated LDL
Where is DHEA-S produced?
adrenals
What type of bilirubin is water insoluble and bound to albumin in blood?
Unconjugated (indirect)
What type of bilirubin is water soluble?
conjugated (direct)
4 diagnostic criteria for DM
HbA1c >6.5%
FPG >126
OGTT 2 hr >= 200 (75g ora glucose load)
Random plasma glucose >=200
Which patients have macro CK type 1?
healthy elderly women
Which patients have mitochondrial CK (macro-ck type 2)?
advanced malignancy
What does prealbumin bind in the serum?
thyroxine (aka transthyretin)
retinol binding protein: vitamin A complex
Causes of pseudo M-spike on SPEP?
Fibrinogen (incompletely clotted sample hemoglobin (hemolyzed sample) elevated CRP elevated transferrin (beta area) Medicaitons (antibiotics, radiocontrast agents) Serum tumor markers (e.g. CA 19-9)
Define type 1 cryoglobulin
monoclonal immune globulin associated with MM or waldenstrom
Define type 2 cryoglobulin
mixture of monoclonal IgM and polyclonal IgG; IgM has rheumatoid factor activity (anti-IgG)
-most common type
Define type 3 cyroglobulin
mix of two polyclonal Ig’s, typically IgG and IgM; IgM has rheumatoid factor activity
What is the most common cause of mixed cryoglobulinemia (type 2+3)
HCV
Sx include leukocytoclastic vasculitis, arthralgia, LAD hepatosplenomegaly, anemia, sensorineural hearing deficits, MPGN type II
what medical conditions can cause pseudohyponatremia?
hypertriglyceridemia
hypercholesterolemia
hyperproteinemia
(due to decreased water content of plasma)
What cancers can secrete PTHrp?
SCC lung, head and neck, skin ,cervix and esophagus
breast ca
T cell lymphoma
What forms of PTH are biologically active?
intact PTH
N-terminal PTH
-rapidly cleared from blood T1/2=5 mins
What is cause of increased BUN/creatinine ratio?
normal 10:1, if greater than 20:1 prerenal azotemia (due to hypoperfusion)
Most common cause of false pos b-hCG
heterophile antibodies
Quad screen showing low AFP, low uE, raised hCG and raised DIA
Trisomy 21 (Downs)
Quad screen showing low AFP, hCG and uE
Trisomy 18 (edwards)
Quad screen showing elevated AFP, normal hCG and low uE
NTD
What is metabolite of serotonin (5-HT) that is produced by carcinoids?
5 hydroxyindoleacetic acid (5-HIAA)
excreted in urine
What do foregut carcinoids produce?
histamine, catecholamines, 5 hydroxytryptophan (5-HTP)
What do midgut carcinoids produce?
serotonin only
What do hindgut carcinoids produce?
usually nothing! non-secretory
VMA is a metabolite of what
norepi–>normetanephrine–>vanillylmandelic acid (VMA)
epi–>metanephrine–>VMA
What two metabolites are elevated in neuroblastoma?
VMA and HVA (homovanillic acid; final breakdown product of dopamine)
At what time points does cortisol trough and peak?
Trough midnight
Peak 8am
TWO MOST COMMON CAUSE CONGENITAL ADRENAL HYPERPLASIA
- 21-HYDROXYLASE DEFICIENCY
2. 11-HYDROXYLASE DEFICIENCY
What is responsible for the majority (70%) of kidney stones?
Calcium oxalate
What metabolite is elevated in CAH
17 hydroxyprogesterone
Increased osmolar gap but normal anion gap. What ingested?
isopropanol
osmolar gap calcuation
osmolal gap=osmolarity measured-osmolarity calculated
=osmolarity measured-(2[Na]+glucose/18+BUN/2.8)
*normal=10
Anion gap calculation
anion gap=Na-(Cl+HCO3)
Causes if metabolic acidosis with increased anion gap?
MUDPILES
methanol, uremia, DKA, paraldehyde, lactic acidosis, ethylene glycol, salicylate
Causes if metabolic acidosis with normal anion gap?
diarrhea, ureterosigmoidoscopy, NH4Cl, carbonic anhydrase inhibitors, TPN, RTA
2 potential causes of increased osmolar gap and increased anion gap?
Methanol or ethylene glycol
What inhibits prolactin secretion?
Dopamine
Patient with elevated serum osmolarity, elevated serum sodium, and low urine osmolarity. When they are given a dose of ADH, their urine becomes concentrated (osmolarity increases from ~100 to ~700 mOsm/kg). What do they have?
Central diabetes insipidus
Patient with lung disease with decreased serum osmolarity, decreased serum sodium, and elevated urine osmolarity. What do they have?
SIADH
Which drug has benzoylecgonine as a metabolite
cocaine
Which HLA types are associated with T1DM
HLA-DR3
HLA-DR4
Which HLA types are associated with celiac
HLA-DQ2 95%
HLA-DQ8 5%
