CC of renal phys and disease Flashcards
What is the value of Na+ in the ECW normally?
140 mEq/L (range 135-145meq/L is okay)
Osmolarity =
total solute/ECF volume
What is the normal expected urine output for a day?
1- 1.5 L/day (get about ~.5 L in total insensible loses) *this is apx = to intake of water/day)
The goal is to maintain isotonicity. In the case of hypertonicity– what happens?
Stimulate hypothalmic Rs–> INCREASE thirst to increse H20 intake INCREASE ADH release to increase renal water retention
The goal is to maintain isotoniity. In the event of hypOtonicity, what is the body’s response?
Inhibit Hypothalmic Rs Decrease thirst to decrease H20 intake Decrease ADH release –> renal water excreation
ADH is stimulated when plasma osmolarity is in the range of: when % blood volume loss is:
At plasma osmolarity of 290 Osm start to see sharp increase in ADH release At % blood loss of 7-10% start to see sharp increase in release of ADH
ADH levels are ____ in dilute urine and ______ in concentrated urine
Low High
Pt that drank tons of water in water contest had headache, found dead in apt later with serum Na at 114 meq/L. What happened?
Body failed to maintain isotonicity She would be HYPOtonic that should cause decreased thrist, decreased release of ADH and increased urine output.. she didn’t stop drinking
What are signs and symptoms of Hyponatremia and when are they most common
when change in Na happens rapidly Nausea, Vomiting, Weakness, Headache, Lethargy, Seizures, Respiratory, Depression, Death
Example of appropriately elevated ADH: Inappropriate ADH elevation:
app: volume depletion inapp: • Cancer (eg small cell lung), CNS disease, Pulmonary disease, Drugs, Narcotics, Antiemetic, SSRIs, HIV
What can the following lead to: Excessive water intake • Hypotonic fluids • Other irrigants Aletered renal water hanling • Chronic kidney disease
altered water balance
______ is the primary determinant of ECF osmolarity
• Serum Na
ECF osmolarity is tightly regulated by
changes in thirst and ADH secretion
Excretion of a dilute urine (osm < 100 mOsm/kg) is required to prevent _______ due to increased water intake
hypoosomalarity
• Inappropriately elevated ADH can precipitate hyponatremia and hypoosmolarity because:
urinary dilution is impaired (osm > 300 mOsm/kg)
Define GFR and it’s normal value
GFR: amount of plasma filtered through glomeruli per unit time (~90-125 mL/min)
• Nitrogenous waste product of protein metabolism • Less accurate indicator of GFR than creatinine
Blood Urea Nitrogen
Why is BUN less accurate then creatine as an indicator of GFR?
due to variation in: – protein intake – catabolic rate – tubular reabsorption • Useful in conjunction with creatinine in the differential diagnosis of renal disease
• Breakdown product of skeletal muscle • Production remains constant over time • Filtered at the glomerulus (like inulin) and can be used to estimate GFR
Serum Creatinine
Serum levels are______ proportionate to GFR
inversely (GFR~100/Cr)
Limitation of using creatine for estimate in GFR
creatinine is also secreted in the nephron and creatinine clearance overestimates GFR
Describe the releationship of GFR to serum creatine
serum creatine from 1 to 2 we see change in GFR = 50 ml/min
from 2 to 3; change in GFR = 25 ml/min
as serum creatine increase and kidney funx decrease, GFR decrease exponentially
What is the best way to measure GFR?
Renal clearance of inulin
GFR = Uinulin x V/ Pinulin
Assuming the following values, what is our GFR?
Pinulin = 1mg/ml
V = 1ml/min
Uinulin= 125mg/ml
Equation for GFR:
[Uinulin x V] / Pinulin
125mg/ml x 1ml/mg / 1mg/ml = 125ml/min
What is the equaiton for measuring Creatine clearance
Creatine clearance = Ucreat x Uvol/ Pcreat
A pts primary care doc asks you to start pt on dialysis bc his GFR is 5 ml/min. You decide that you will IF his GFR is truly tht low. You collect a 24 hr urine sample (1440 mins) to calc Creatine clearance. Uvol = 2.1 L with Ucreat = 95mg/dl. The serum creatinine is 7.0 mg/dl and BUN is 44mg/dl
What is the pts Creatine clearance?
Creatine Clearance = Ucreat x Uvol/ Pcreat
** you need to take into account the collection was over 24 hours or 1440 mins–>
Ucreat x Uvol/ Pcreat x 1440 mins
95mg/dl x 2100 ml
7 mg/dl x 1440min
= 19.8 ml/min
When is dialysis indicated?
When pts GFR is less then 10
What is the Cockcroft-Gault Equation?
Creatine clearance = (140-age) x weight (kg)/ Serum Cr x 72
*if female, multiply answer by 0.85
Serum creatinine can be used to estimate_____:
• GFR is ~ ______
GFR
100/serum creatinine
- CrCl can be calculated by
- CrCl can be estimated by
U●V/P
Cockcroft-Gault
Serum creatinine based GFR estimates can be
inaccurate due to extremes of
age, BMI, or muscle mass
If ECF is contracted, we will cause barareceptor ______ which then cauases _____ sympathetic tone
activation
increased
Increased sympathetic tone d/t ECF contraction leads to:
increased renin secreation–> causes increase of Ang II–> increased aldosterone –> increased Na reabsorption to increase effective circulating volume
+
increased sympathetic tone directly increase tubular Na+ reabosorption.
Control of tubular Na Reabsorption is controlled by a number of inputs. These will effect tubular Na channels and transporters
– Renal sympathetic tone
– Hormonal
– Blood pressure
What are the 2 Direct Tubular Effects to increase Na reabsorption
• Renal sympathetic nerves:Multiple tubular receptors stimulate Na reabsorption
• Angiotensin II: Tubular receptors and increases activity of proximal tubule Na/H
countertransporter
Actions of Ang II in the Proixmal tubule
Increases Na reabsorption:
- Increases Na+ in/H+ out on the lumen side
- Increases Na+ in/K+ out on the renal IF side
- Increases Na+/HCO3- in to the renal IF
Aldosterone stimulates Na reabsorption in :
– ___of filtered load of Na has its excretion
dependent on aldosterone action
cortical collecting duct principal cells
~2%
How does Aldosterone increase Na reabsorption?
– increases number of luminal Na channels and BL Na/K-ATPases
– Most important stimulus for aldosterone secretion relating to Na balance
-dependent upon renin secretion and therefore baroreceptors, macula densa, and
renal sympathetic tone
Angiotensin II
What is the MOA of ADH on late distal tubules, CDs and collecting tubules
increases produciton and distribtuion of AQP-2 on the tubular lumen side to increaes H20 reabsorption
The systemic response to decreased ECF volume involves:
- Baroreceptor and sympathetic nerve activation
- Activation of Renin-AngII-Aldo system
- Increased ADH
These factors lead to enhanced renal tubular Na and water reabsorption
• Clinically reflected by low urine Na, low FENa, and elevated urine osmolarity
– secreted by juxtaglomerular cells
– converts angiotensinogen –> angiotensin
– angiotensin regulates BP and salt balance
Renin
Erythropoetin (epo)
– produced by _________
– stimulates erythrocyte production in ____
renal cortical tubular cells
marrow
formed in proximal tubule cells
– regulates calcium and phosphate balance
• 1,25 dihydroxyvitamin D production
Increased reabsorption of Na proximal tubule, increased ADH secreation and Activation of baroreceptors are all activated when:
they sense ECF depletion
Increased serum _____ will contribute to hyperparathyroidism
increased serum phosphorus
Low Ca++ leads to increase in _____
Increased PTH
All of these things will be increased in response to increased PTH thats stimulated by low Ca++
Increased vit D2 activtion–> increased intestinal Ca++ reabsorption
increased renal Ca++ reabsorption
Increased Ca++ released from bones
Kidney disease results in _____ 1,25 Vit D prodcution and _____ serum P04
DECREASED 1,25 Vit D production
Increaed serum PO4
Increased serum PO4 and decreased 1,25 Vd prodution lead to what three things
decreased serum Ca++
decreased CaR
Decreased VDR
–> all leads to increased PTH
Chronic kidney disease:
•Decreased_______ production leading decreased calcium absorption, hypocalcemia, and 2° hyperparathyroidism
calcitriol
Chronic kidney disease:
Leads to________ retention leading to 2°hyperparathyroidism
phosphorus
Secondary hyperparathyroidism leads to :
increased bone turnover and extraosseus calcification
