EXAM 2 NEPHROLOGY Flashcards
Fluid and electrolytes homeostasis First step = ◦ RBF depends on
production of glomerular filtrate from the renal plasma systolic BP and circulating BV
◦ GFR depends on
RBF
Kidneys receive _______CO over wide range of
20-30%; BP via auto-regulation
◦ Best perfused organ per gram of weight is the ______
Kidney
Renal hormones of autoregulation ◦ Vasodilators: PIND
prostaglandins E and I2, dopamine, nitric oxide
◦ Vasoconstrictors: ATEA
angiotensin II, thromboxane, adrenergic stimulation, endothelin
Nitrous oxide
increase GMP
Too much blood flow
Trauma There is delicate low pressure
RBF + GFR ______during the first
Double in first 2 weeks of post natal life
GFR estimated based on
Cr and height
GFR =
Height(cm) x k /serum creatinine
Better for function is ______but _____gives a close estimate
Creatinine Clearance; GFR
the K constant is dependent on
Age
◦ Kidneys regulate total body Na+ balance and maintains (2) Filters _______mEq Na per day but excretes ___due to
normal extracellular and circulating volumes 25000; 1% efficient resorption
The Proximal tubule resorbs ____-____% and Ascending limb of loop of henle _____% and distal tubule____% (____think PAD)(great to least)
50-70%, ascending limb of loop of Henle 25%, distal tubule 10%
Serum OsmolaLity controlled by (what hormone) Stimulated by ______(HINVOIS)
ADH, Increasing in plasma osmolaLIty , Hypotension, NV, opioids, inflammation and surgery
Normal serum osmolarity
275-295 mosm/kg
Osmolarity Osmolality
L/mosm Kg/mmosm
Potassium Regulation depends on_______ ◦ Binds to receptors in → ______
aldosterone distal nephron; ↑ K+ excretion
◦ Neonates cannot regulate or do this efficiently_______, they normally have ______ Normal K+ 0-1months; 1month - 2 years
- Potassium regulation (neonates less efficient at excreting potassium loads) - ↑ K+ 4-6 4-5.5
Secrete Potassium: Name of the cells
Principal cells
Hyperkalemic patients are often
Acidotic
As H+ inside the cells, potassium
Leave the cell –> patient becomes Hyperkalemic
Treatment of hyperkalemic
Albuterol insulin, Calcium gluconate B-agonist
Acid-base balance where is almost all bicarb reclaimed ________ Is bicarb lost in neutralization regenerated? New bicarb= ___________in ________
◦ Almost all bicarbonate (HCO3-) reclaimed in proximal tubule ◦ Bicarb lost via neutralization of acid = regenerated New bicarb = product of breakdown of carbonic acid (H2CO3) in distal nephron
Infants normally slightly _____have less ____compared to adults They have limited _______
Infants normally slightly acidotic (pH=7.37) have less bicarb (22 mEq/L) compared to adults ◦ Limited in ability to respond to acid load, esp. premies
Acute Kidney Injury = _____onset ◦ Multifactorial; classified as
(AKI, formerly acute renal failure) = abrupt prerenal, intrarenal, postrenal
2 issues in AKI you must know
- deterioration in ability of kidneys to clear nitrogenous wastes (urea and creatinine) + - ↓ability to excrete solutes and maintain normal water balance
◦ Clinical presentations of renal insufficiency:
edema, HTN, HyperK+, uremia
Children more likely to have renal disease from______such as (SS)
systemic diseases (e.g., sickle cell disease, systemic lupus erythematosus)
Harmful to kidney among other INTRARENAL
Contrast dye Acute Glomerulonephritis NSAIDS Antibiotics (Aminoglycosides, AMPHOTERICIN B)
POST-RENAL
Obstruction (stone, tumor, BPH)
Pre-renal is (LCS) Exacerbated by : NSAIDS, ACEI, ARBs.
the most common Loss of ECF , cardiac failure, sepsis DIMINISHED RENAL PERFUSION Major hemorrhage, V/D, severe burns, CHF
Intra-renal causes
20-30% Infants: Birth ASPHYXIA, SEPSIS, cardiac surgery Older: TUHS (Trauma, Uremia (hemolytic), sepsis
Post renal Obstruction can be intrarenar
1.INTRARENAL Tumor lysis myoglobinuria Hemoglobinuria Meds: acyclovir, antiviral 2. URETER: Stones, compression pressure from lymph/tumor Post renal
Exact pathophysiology of AKI________
what factors increases renal vasoconstriction?
Unknown Profound renal vasoconstriction –>
GFR Increase renal vasoconstriction RAAS , SNS and endothelial dysfunction (Increase endothelin, decrease NO)
Therapy for Vasodilation
Prostaglandin, Dopamine, ACEI, CCB Endothelin antagonists, however does not significantly reverse AKI
Opposing forces to pressure tissue
Protein want to hold on fluid Decrease GFR Less pressure pushing forward, same pressure pushing backwards, DECREASE GRF–> decrease in Renal output
AKI can result also from
renal tubule cell injury
Nephrotoxin or ischemic insult
Obstructs within minutes Decrease GFR via obstruction of lumen of tubule.
With reperfusion injury after ischemia metabolic BYPRODUCT call in
Neutrophils.
Reperfusion injury increases intracellular adhesion molecule 1 (ICAM-1) on endothelial cells promoting the adhesion of circulating neutrophils and their eventual infiltration into the parenchyma.
Blood flow down–>
ischemia –> Low GFR –> Dialysis
PRE renal AKI Look at the _______ .
if ratio____Prerenal
if ratio______ renal
Prerenal = FEna _____%children ___% infants
Intrarenal = FEna > __%
What does FEna Stands for
Look at BUN: CR ration >20 Prerenal <20 Renal
FENA prerenal Children < 1% 2.5% infants
Fena INTRARENAL > 1%
Differentiate between pre-renal
look at FENA Renal US
Interventions : Hypovolemic
Fluid resuscitation of at least 20ml/kg over 30-60min
RULE OF THUMB: give 500 or less
Diuretics should only be used
After circulation volume is adequate restored
Dialysis for patients- indications
When is dialysis indicated?
Hyperkalemia Fluid overload refractory to diuretics
Severe metabolic acidosis
S/S of uremia (pericarditis, encephalopathy)
BUN approaches 100mg/dL
