Renal Flashcards
What does AKI stand for?
Acute Kidney Injury (FYI: used to be called acute renal failure)
When does urine begin to be excreted in the fetus?
9th wk gestation
What is the major component of Amniotic Fluid after 16-20 wks gestation?
Urine
When is Nephrogenesis complete?
32-36 wks, most literature says 34 wks at earliest.
Is post-natal Nephrogenesis accelerated after pre-term birth (like the skin)?
No. It develops at same rate as if still in-utero and may be Abnormal.
T/F Preterm babies develop all the Nephrons they would have made had they stayed in Utero.
False. They do not get all the Nephrons they would have if term.
Preemies are a set up for?
Chronic Kidney Disease
T/F, many preemies who have kidney problems will develop end stage renal failure later in life.
True
The term kidney has ______ nephrons
~ 1 Million (range 300k-1.8 M)
Name the 2 Parts of the Nephron
- Glomerulus
2. Renal tubule
Name the 2 Types of Nephron
- Cortical Nephron-glomerulus and tubular system in outer Cortex
- Juxtaglomerular Nephron-tubular system of the Nephron penetrates into Medulla
T/F 1 Collecting Tubule drains to a Collecting Duct
False. Many Collecting tubules go to a single Collecting Duct
Define Pelviectasis/Pyelectasis
Dilation of the Renal Pelvis
Is Pelviectasis/Pyelectasis common?
Yes, fairly common
What is Mild Renal Pelviectasis?
4-10 mm-mild dilation in 2nd Trimester
Does Mild Renal Peviectasis resolve?
Yes,97% resolve. Is probably just a stage in development.
Define Hydronephrosis.
Dilitation >10 mm on US
How common is Hydronephrosis, does it resolve, need F/U?
1-4% pregnancies, more male
Many prenatally dx will self-resolve
Needs F/U, obstruction may be cause
What are the 3 main functions of the Renal system?
- Eliminate Nitrogenous waste
- Control Composition of blood (electrolyte and acid/base balance)
- Endocrine Function (Erythropoetin, Calcitriol, Renin)
Erythropoetin is secreted in response to? What does Erythropoetin do?
Hypoxia. It is secreted from the kidney cells.
It stimulates the Bone Marrow to make RBC’s.
What is the function of Calcitriol?
It is the active form of Vit D. Works with Parathyroid H. to maintain Ca++ balance and make bones.
What is Renin responsible for?
Keeping the b/p up.
It controls the volume of blood (b/p).
In the Glomerulus, there are Afferent Arterioles and Efferent Artioles. Which is wider?
Afferent Arteriole
Describe what determines how much Hydrostatic Pressure is in the Bowman’s Capsule.
It is dependent on how dilated the Afferent Arteriole is and how constricted the Efferent Arteriole is.
Each Glomerular tuft has about how many capillaries in each?
about 50
Due to the Hydrostatic pressure in the Glomerulus, what happens?
H2O and small solutes are filtered out and enter the proximal convoluted tubule.
Can RBC’s filter through the proximal convoluted tubule?
No, usually too big to pass through the small slit-like pores in the glomerulus–They circle around and go back out through the Efferent Arteriole, back to circulation.
What does GFR stand for and what does it tell you?
Glomerular Filtration Rate.
Tells you how well the kidney is functioning.
What is the Definition of GFR?
The amount of filtrate that flows out of all Renal Nephrons of both Kidneys in 1 Minute.
At Term the GFR is ____% of Adults.
Preterm at 28 wks is ____% of Term.
50%
50%
About how long does it take a Term baby to double GFR?
How long does it take a preemie to double GFR?
What is it determined by?
When does it reach Adult values?
~ 2 Wks
As long as 6 wks for Preemie
Determined by Renal Vascular Resistance (RVR)
Reaches adult values by 2 yrs
The Tubular system selectively reabsorbs or secretes various substances in different portions by what mechanisms?
Active and Passive transport
Which tubule is the “work horse” reabsorbing most everything..the Proximal Convoluted Tubule or the Distal Convoluted Tubule?
The Proximal Convoluted Tubule
In addition to absorption and secretion, what are the other functions of the Proximal Convoluted Tubule?
pH balance:
- H+ secretion/HCO3 reabsorption
- Phosphate/Ammonia buffer systems (generate new HCO3)
What is the main anion Actively transported in the Loop of Henle?
Name the 4 other cations Passively transported with it.
Cl-
- Na+
- K+
- Ca++
- Mg+
Is H2O reabsorbed in the Loop of Henle?
No.
Name the 3 Hormones in the Distal Convoluted Tubule and Collecting Duct that fine tune Na+, K+, H+, Ca++, and H2O that haven’t been reabsorbed in the rest of the tubule.
- Aldosterone
- Antidiuretic Hormone (Argenine Vasopression-AVP)
- Parathyroid Hormone
What Hormone is assists with H2O reabsorption?
ADH (Anti-Diuretic Hormone/Argenine Vasopression AVP)
What do the cell so of the Macula Densa sense?
Osmolarity of filtrate
Osmoreceptors
What does the Macula Densa do if they sense high osmolarity of the Filtrate?
Signals the Juxtaglomerular Cells to secrete Renin (which exits the efferent arteriole to circuation)
Juxtaglomerular cells sense what?
Stretch
Baroreceptors
Where are most Juxtaglomerular cells located, the Afferent or Efferent Artirole?
Afferent Arteriole
What does Aldosterone do in the Distal Tubule?
What does it cause systemically and how?
It controls reabsorption of Na+
(2-5%, the last little bit)
Increased b/p because H2O follows Na+
What is secreted in exchange for the reabsorption of Na+ ions?
K+ & H+ ions are secreted in exchange for Na+.
A ____ amount of Na+ reabsorption in the distal tubule = _______ amount of Urine formation.
Small amount Na+ = Large amount Urine formed
you hold on to the urine, don’t excrete it
ADH tells the distal tubule what?
How much H2O it is going to retain.
ADH is produced where?
It is stored where?
It acts on the ____ _____ and ________ ___ to _________reabsorption of H2O
Hypothalamus
Anterior Pituitary
Distal Tubule and Collecting Duct to Increase
ADH allows for excretion of what type of urine?
Concentrated
Preemies are __________ to ADH.
Hypo-responsive to ADH
What syndrome is A/W excessive ADH secretion?
What types of babies are affected by this?
SIADH (Too much H2O retained)
MAS, Asphyxia, IVH, RDS, Pneumothorax
Parathyroid Hormone are responsible for reabsorbing?
What 2 locations does it act?
Ca++
Intestine and Distal Tubule
If PTH is present in the Distal Tubule, what happens to Ca+?
Ca+ is absorbed
if no PTH, No Ca+ absorption
A Renal insult between 32-35 wks effects what?
The final number of Nephrons.
What happens in the Glomerulus of a Preemie?
- Immature Autoregulation of Afferent Arteriolar Dilation & Efferent Artiolar Constriction.
- Underdeveloped and Hyporesponsive Receptor sites on the arterioles.
The Tubules have ______to increase absorption (like the intestines)
Microvilli
In a preemie, drug clearance is increased or delayed?
Delayed
Preemies have a shorter/longer underdeveloped Loop of Henle?
Shorter, underdeveloped loop
Preemies have hyporesponsiveness to Aldosterone in the distal collecting tubule causing what?
Loss Na+
Retention K+
Retention H+
Preemies have low/high circulating levels of ADH? Hyper/Hyporesponsiveness to ADH?
Low levels
Hyporesponsiveness (limited urine concentrating ability)
What is the HCO3 reabsorption threshold of a term baby?
Of a Preemie?
Micropreemie?
Term: 21 mEq/L
Preemie: 18 mEq/L
Micropreemie: 14 mEq/L
How do you Tx Metabolic Acidosis in Preemie d/t renal immaturity?
- Use 1/2 Na Acetate instead of 1/2 NS in Arterial infusions
- Omit Cysteine from TPN until pH normal (is essential but added as Cl-)
- Add Na+ and K+ to TPN as Acetate
In an infant with respiratory issues, keeping a preterm infant slightly Alkalotic will keep pH normal while allowing for what?
Permissive Hypercapnia (compensating for resp. acidosis)
Preemies are in a Negative or Positive Na+ and H2O balance the 1st few days?
Negative (normal adaptation)
True/False: Preterm and Term babies have a limited ability to excrete a Large Na+ or H2O load?
True
A “wet baby” is a ____ baby. It is A/W?
Bad. Keep them dry.
Severe RSV, CLD, Pulmonary Edema, CHF, PDA, IVH, NEC
What range should you target Na+ in the transitional period?
When should you add Na+ to the IVF?
140-145 mEq/L
Not for first 24-72 hrs or until Serum level is <140 mEq/L
What 2 things can cause Hyponatremia?
- Excessive fluid intake
2. Inadequate supplementation
What 2 things can cause Hypernatremia?
- Inadequate fluid intake
2. Insensible water loss
What is the avearage daily intake Na+ (per kg)
2-4 mEq/Kg/day
Where do you want the serum Na if baby is on Diuretics?
130-135 mEq/L
NS is = to _____mEq/L
0.154 mEq/L
What 2 electrolytes are essential for optimal growth?
Na+ & K+
Avoid adding K+ to TPN until what 2 things happen?
- Serum K+ starts to fall AND
2. UOP is WELL established
Prerenal AKI is due to ?
Hypoperfusion of the Kidney
Is Prerenal AKI reversible?
Yes, if Dx’d and Tx’d early
the kidney is intrinsically normal
What can cause Prerenal AKI?
Maternal meds: ACE inhibitors, NSAIDS, Cyclooxygenase inhibitors (celebrex)
Antepartum hemorrhage
Birth Asphyxia
Hypothermia (decrease by 2 deg C can cause severe decrease GFR)
PostPartum Hemorrhage (IVH, Adrenal Hemorrhage, Subgaleal Hemorrhage)
Hypovolemia
Cardiac
Hypoxia
Obstruction of Venous Return
Septic Shock
Metabolic problems
Polycythemia
ECMO
Surgery w/cardiopulm. bypass
Meds that decrease blood flow (Indocin, Ace, Pheylepherine eye drops)
What is Post Renal AKI?
Damage due to Mechanical Obstruction of Urine Flow somewhere in the Urinary System
What is the most common cause of Post-Renal AKI in Males?
Posterior Urethral Valves (happens 4th wks gestation-d/t caudal end Wolfian Duct abnormal anastamoses).
10-15% need kidney transplant
Besides posterior urethral valves, what are some other causes of Post-Renal AKI?
Ureteropelvic Obstruction Ureterovesical junction Obstruction Urogenic Bladder Urethral strictures/Obstructed catheter Teratoma Calculi Renal Candidiasis (Fungal balls)
What does AKI stand for?
Acute Kidney Injury
Describe AKI
Intrinsic Renal Failure
~30% all NICU admits
EVERY Infant admitted to NICU is AT RISK
Any prolongation of Prerenal or Postrenal failure will lead to_____ ______ to the kidneys.
Structural Damage
What is usually the 1st presenting sign of AKI?
Low U.O.
All infants void w/in ____ hrs.
Normal U.O. is __mL/kg/hr
Oliguria = __ mL/kr/hr
24
2-4 mL/kg/hr
<1 mL/kg/hr
Abdominal masses are most likely to be?
Renal
If an infant has a AKI, what other systems should be closely observed?
GU/Genital/ears
You should get a Renal US with what type of cord?
2-vessel cord
Congenital causes for renal/urinary system anomalies:
Renal Agenesis
Polycystic Kidney Dz
Congenital Nephrotic Syndrome
Renal Hypoplasia/Dsyplasia
Besides congenital, what are the other reasons for AKI?
Renal Vein Thrombosis (IDM w/hyperviscosity/polycythemia) Renal Artery Thrombosis (have cold legs) UAC Sepsis DIC (microthrombi in glomerulus) Nephrotoxins
What is the underlying pathway of AKI regardless of cause?
Decreased GFR
If baby is on Abx, and Creatinine is increased, what should you do with the Abx?
Space doses out (Decrease frequency). Give same dose (do not decrease dose).
What would you see on UA as evidence of Tubular Damage?
Casts, Tubular cells, Protein (trace-2+ is o.k. in preemie)
U. Cath taped to thigh of male infant may cause?
Where is it best to tape it?
Damage to Posterior Urethra
Tape it to the lower abdomen
How often can a diagnostic fluid challenge/lasix be performed?
1-2 x’s max
What does a fluid challenge r/o?
How is it performed?
Hypovolemia (pre-renal failure–would have Increased U.O. if pre-renal failure +)
10-20 mL/kg NS over 1-2 hrs + Lasix 1-1.5 mg/kg/dose IV
Is there evidence for low dose Dopamine for renal perfusion?
No
Hydrocortisone is for…?
Refractory Systemic hypotension in preterms with Adrenal insufficiency. (send cortisol level)
Is BUN a specific marker for AKI?
No
Is Creatinine a specific marker of AKI?
What does early level represent?
When may you see a rise in Crt?
Yes
Maternal Creatnine
After 25-50% of renal function is lost
If Creatinine doubles ____% of renal function has been lost
50%
Using lowest baseline Serum Crt what 3 items may indicate AKI?
SCr rise > 0.3mg/dL w/in 48 hrs
SCr rise >1.5 - 1.9 times baseline w/in 7 days
UOP >0.5 - <1 mL/kg/hr
Fractional excretion of Na+ (in urine) may be used to Dx ____.
What must be complete for it to be accurate?
AKI–differentiates between prerenal and intrinsic renal failure >32-34 wks
Nephrogenesis
Fractional Excretion of Na+ is not useful if…?
Lasix has been given
With AKI, hyponatremia is due to what?
The hyponatremia is then what?
Decreased UOP and fluid retention Dilutional hyponatremia (too much free water)
With AKI, how do you tx?
Cut fluids to insensible H2O loss + UOP (bare bones)
What is term insensible H2O loss?
Preterm?
~30-50 mL/kg/day ~30-65 mL/kg/day 1000-1250gm 60-70 mL/kg/day 750-1000gm 100-150 mL/kg/day <750 gm (decrease amt if on vent or increased humidity)
Is hyponatremia due to high output renal failure a good sign?
Yes. Possibly d/t glomerulus recovery but tubule hasn’t caught up yet.
What happens in Hyponatremia d/t high out put renal failure.
How long do you see this?
BUN and Crt begin to decrease
Lasts 24-28hrs
In Hyponatremia, when would you give Na+?
What dose?
120 mEq/L AND good UOP
10 mL/kg NS over 30-60 min
How do you tx Na < 120mEq/L ?
What might this Na level result in?
“hot salts” 3% Na+, osmolarity 1.025mOsm/L–give 1-3mL IV over 15 min
May result in seizures–seizures usually stop after increase of 3-5 mEq/L in serum
If Na is >120 mEq/L, and not seizing, best to correct Na over what time frame?
How?
What is the max increase of serum Na+ mEq/L in 24 hrs?
Why?
Correct slowly over 24-48 hrs
Add Na+ 1-3mEq/kg to IVF
No more than 8mEq/L in 24 hrs—Can cause dangerous fluid shift in brain
What is the Na+ replacement formula?
Wt (kg) x 0.6 x (CD-CA) = dose (Na mEq)
Give 1/2 this amount over 12-24 hrs
With AKI, may also see hyperkalemia. What is the serum level?
What clinical changes might you see?
6.5-7mEq/L
-EKG changes:
peaked T-waves
Flat P waves–>prolonged PR int–>eventual absent P waves
Wide QRS
Sine wave pattern
V. Fib/Asystole
How would you tx Hyperkalemia?
Remove all K+ from infusions
Give 10% Ca Gluconate (heart protective-only if EKG changes other than just peaked T’s) Dose: 100-200mg/kg/dose over 10-30 min NOT in UAC
Continual Cardiac Monitoring
What 3 things could you do to “hide” K+ from baby’s serum?
Why?
- 1/2 strength NaHCO3 (1-2mEq/kg 10-30 min)–flush line before & after w/Ca+ infusion
- Albuterol Neb
- Insulin/Glucose
- -All 3 drive K+ into the cells temporarily
How can you Rid the body of K+?
Lasix 1mg/kg IV Q 12 hrs
Cation exchange resins (kayexelate Rectally or OG/NG) ***exchanges K+ for Na+.
Binds K+ and is excreted in stool.
When would you not want to use Kayexelate?
<29 wks
GI problems
Poor GI perfusion
what is the ionized hypocalcemia level?
<4 mg/dL-term and preterm
How do you treat acute Hypocalcemia?
Calcium Gluconate 100-200 mg/kg PIV/10-30 min w/Cardiac monitoring.
*If heart failure-use CaCl (doesn’t have to be metabolized 1st–but is 3x more caustic to veins)
The kidney is the primary route of _____ elimination.
Phosphorous
What does Phosphorus bind with?
How do you tx hyperphosphatemia with AKI?
Phos binds w/Ca++
Dietary Ca++ to bind PO4 (Calicum carbonate)
Phosphate binders (Aluminum hydroxide) “Amphagel”
What is the normal Phosphorus range for Term? Preterm?
- 2-7mg/dL
4. 2-8.5mg/dL
W/AKI keep pH between?
Why
7.2-7.25
Tx of acidosis increases Ca++ binding to Albumin–>decreased circulating iCa
Which as better prognosis, Non-Oliguric AKI or Oliguric AKI?
Non-Oliguric AKI
The Prognosis is AKI depends on ?
The Primary Cause
What 4 factors do not influence prognosis of AKI
- Birth Wt
- APGAR score
- FeNa
- Peak Creatinine and BUN
What type of diet would an infant in Chronic Renal Failure need?
High protein 3-4 g/kg/day
High calorie 150-180 Kcal/kg/day
Name the 2 forms of dialysis
- Peritoneal
2. Hemdialysis (have to be big–wt)
With Kidney transplant, is an adult kidney or kid kidney best?
Why?
Adult
Increased blood flow, pressure, & volume
It’s ok to use a catheterized urine sample for culture unless looking for what?
Fungus, especially in uncircumcized male
Name 4 indications of UTI on UC
- Leukocyte esterase
- Nitrites (bacteria convert Nitrates to Nitrites)
- Casts (of WBC’s)
- Neutrophil gelatinase
What is Sensitivity?
A test’s ability to correctly label those who have the condition (Positive–you have it, it shows in test)
What is Specificity?
A test’s ability to correctly label those who do not have the condition (Negative)
Is prophylactic Abx use for babies at risk for UTI’s controversial?
Yes.
would use Amp, Amox, Septra
*Circ is recommended in this case
Vancomycin kills any organism _________ kills.
Ampicillin
Which grades of Vesicoureteral Reflux will an infant outgrow by 5 y/o?
1-3
Which grade of reflux will likely need kidney removal?
5
The PO dose of Lasix is ___ times that of IV dose.
Why?
Are PO/IV effects the same?
2 x’s
It has less bioavailability
Yes, same effect
What is the major site of action of Lasix?
Loop of Henle
How does Lasix work?
It blocks active Cl- reabsorption -blocks passive Na+ reabsorption -blocks passive K+ reabsorption -blocks passive Ca++ reabsorption Only a small amount are reabsorbed at distal tubule through hormones (and H2O via ADH) Rest are: "wasted" out of the body
Name the side effects of Lasix
Hyponatremia, Hypocalcemia, Hypokalemia, and Hypochloremia.
Also Nephrocalcinosis, Ototoxicity
What does Hypochloremia do?
Causes metabolic Alkalosis (Cl has inverse relationship w/HCO3)
How does the body try to compensate for hypochloremia?
The lungs retain CO2 by hypoventilating.
If you are trying to correct hypochloremia r/t Lasix, Give ____ to replace. Not______. Why?
Give KCl Not NaCl (sm. amt ok in <34 wks d/t Na+ losses from renal immaturity) H2O follows Na, defeating the purpose of the Lasix-vicious cycle.
The body will normalize ____ at the expense of _____.
Normalizes K+ at the expense of Na+.
As K+ leaves cells to maintain serum K+, Na+ moves into the cells (causing hyponatremia).
Once K+ is restored, Na+ will move back out of the cells.
When giving diuretics, and treating hypochloremia and hyponatremia, what level do you want Cl-? Na+?
Cl- up to 95
Na+ 130-135mEq/L
Is Lasix ototoxic?
Yes. Do not combine w/Gentamicin if possible.
Renal calcifcations can occur in babies after what cumulative dose?
When do they resolve?
20mg/kg
Resolve 6-12 months after d/c Lasix
What is the major site of action of Thiazides?
Distal tubule–not as effective as Lasix as only a small amount of Na+ is absorbed there.
What electrolytes are lost with use of Thiazides? Why?
Na+, K+ (due to increased UO), Cl- (folllows Na+ & K+)
Which electrolyte is spared when giving Thiazides vs. Lasix? Why?
Ca++. Thiazides stimulate PTH secretion or potentiate it’s effects.
Spironolactone’s major site of action is?
Distal tubule and collecting ducts.
Spironolactone is ___sparing.
It inhibits what hormone?
Is the diuretic effect as good as Lasix?
K+.
Inhibits Aldosterone (thereby inhibiting Na+ reabsorption and inhibiting secretion of K+)—may not work in preemie who is hyporesponsive to Aldosterone
No.
What is the equation for Fractional excretion of Na+?
Urine Na x Serum Cr / Urine Cr x Serum Na
U Na x S Cr / U Cr x S Na
