Renal & Electrolytes

What comes in a basic metabolic panel (BMP, CHEM-8)?

◼sodium

◼potassium

◼chloride

◼TCO2*

◼BUN

◼creatinine

◼glucose

◼calcium

What comes in a comprehensive metabolic panel (CMP, CHEM-14)?

Includes BMP and liver panel:

AST

ALT

ALP

total bilirubin

albumin

total protein

What is the role of the kidneys?

filters cellular waste,

water, electrolyte, and acid base balance

renin angiotension system

vitamin D and EPO production

What is the main difference between comprehensive metabolic panel and a basic metabolic panel?

liver panel

What is the functional unit of the kidney?

nephron

What is the function of the nephron?

glomerular filtration, tubular absorption, and tubular secretion

What is the term for the rate at which fluid is filtered through the kidneys, non-selectively?

GFR (glomerular filtration rate)

Should plasma proteins and protein-bound substances be in the filtrate?

no (substances <70,000 daltons should not pass through)

How is GFR measured?

creatine clearance or equations to serum creatine values

(cockcroft gault, MDRD, CKD-EPI)

How much blood does the kidney process daily?

180 L

How much urine is produced each day?

1-2L

What equation takes into account serum Cr, age, weight, and sex?

cockcroft gault

What equation is more accurate for eGFR that does not use weight bc the results normalized to surface area- use age, gender, and RACE?

MDRD

What is the most accurate equation of GFR calculations?

CKD-EPI

For GFR in most pts ____ is adequate.

60

How does aging (after 40yo) affect the normal range for GFR?

decreases (about 0.4-1.2 per year)

The lower the GFR, the ___________ the kidney damage.

more significant

Declining GFR indicates _____.

kidney dysfunction

Why dont we use serum Cr to estimate kidney function?

usually doesnt differ based on GFR stimulation

What part of BMP is increased with ingested protein and is affected by liver disease and indicates urea being formed in the liver as an end product of protein metabolism?

BUN

What is freely filtered and excreted by the kidneys and can be used for hydration status?

BUN

What are BUN serum levels dependent on?

▪GFR

▪Proximal tubule reabsorption

▪Functional status of hepatic urea cycle

▪Dietary protein

▪Tissue metabolism

How does overhydration affect BUN values?

decreased

How does dehydration affect BUN values?

elevate

What indicates acute kidney injury/failure and shows an increased BUN?

azotemia

How will the BUN value be affected with azotemia?

increased

What is due to problems in the systemic circulation that decrease blood flow to the kidneys (hypoperfusion)?

prerenal AKI (acute kidney injury)

- issue occurs BEFORE blood reaches the kidneys

These are usually present in what part of AKI?

▪Congestive heart failure

▪Shock

▪Dehydration

▪GI hemorrhage

▪Renal artery stenosis

▪Cirrhosis

prerenal AKI (acute kidney injury)

What is typically due to intrinsic renal disease that will depict what location is impaired?

renal AKI

- issue occurs AT the kidneys themselves

What renal AKI will present with muddy brown casts?

acute tubular necrosis

What renal AKI will present with RBC casts?

acute glomerulonephritis

What renal AKI will present with WBC casts?

acute interstitial nephritis

What is usually due to obstruction in the collecting system after passing through the kidney?

postrenal AKI

- issue occurs AFTER renal filtration in structures distal to kidneys

These are usually present in what part of AKI?

▪Usually does not occur unless bilateral obstruction of ureters

▪Prostate cancer

▪Bladder/cervical cancer

▪Renal calculi

▪Obstructed catheter

post renal AKI

What is the clinical term that describes signs and symptoms associated with end stage renal disease?

uremia

All parts of AKI will cause what affect to the BUN value?

increase

What is a waste product in the blood that comes from muscle activity (directly related to muscle mass)?

creatinine

What is the MC used indicator for renal function?

serum creatinine

These all have what affect on the serum creatine value?

▪Renal disease

▪Hypovolemia

▪Tissue necrosis

▪Medications/drugs

increased

These all have what affect on the serum creatine value?

▪Muscular atrophy, cachexia

▪Pregnancy, SIADH (volume overload)

decreased

What does BUN stand for?

blood urea nitrogen

What are the 2 things that affect the BUN value, and what is normal?

▪Affected by diet

▪May be used for hydration status

▪Normal range 7-20 mg/dL

What value is not affected by diet and is the better indicator for kidney function?

SCr

BUN/creatine ratio are increased with what?

dehydration, CHF, hypoperfusion

What decreases BUN/creatine ratio?

reduced absorption of BUN

What helps determine the cause of azotemia (prerenal, renal, and postrenal)?

BUN/Cr ratio

What is the prerenal BUN/Cr ratio?

>20:1

What is the renal BUN/Cr ratio?

<10:1

What is the postrenal BUN/Cr ratio?

10:1-20:1

What is the formula for serum creatine?

UV/P

Urine creatine * volume of urine= serum creatine

Urine collections over smaller windows for CrCl gives ______ results.

less accurate

How is the urine sample taken for accurate CrCl level?

24 hour urine sample

Decreased CrCl suggests _____ filtration which suggests _______.

decreased, kidney dysfunction

What does increased CrCl usually represent?

high cardiac output (HTN, CHF, even exercise)

Excess albumin in the urine is a marker of _______ regardless of eGFR?

renal disease

What is the normal level of albumin in the urine for healthy individuals?

very small value

What is the preferred test for albumin creatine ratio?

spot urine

What is the value of normal creatinine for albumin/creatine ratio?

<30mg per gram

What is the value of moderately increased creatinine for albumin/creatine ratio?

30-300mg per gram

(microalbuminuria)

What is the value of severely increased creatinine for albumin/creatine ratio?

>300mg per gram

Persistently elevated urinary protein (at least 2 abnormal albumin/creatinine ratio tests over 3 or more months*) is indicative of _________.

CKD (chronic renal failure)

What are some risk factors for screening for kidney disease?

▪> 60yo

▪Diabetes

▪HTN

▪Family history of kidney disease

What is the normal glucose range (blood sugar) for fasting?

70-99

What is the normal glucose range (blood sugar) for non- fasting?

<200

What is the most abundant cation that contributes to the extracellular fluid and essential for transmitting nerve impulses?

sodium (Na+)

What is the normal range for sodium?

135-145

What are the two regulation ways for the renal system?

Renin- ADH system

and

Renin-angiotensin-aldosterone system

A pt presents with N/V/D, abdominal cramps, dry skin, tachycardia, hypotension, headache, lethargy, confusion with muscle weakness, and HYPOTENSION-- what is the likely dx?

hyponatremia

A pt presents with N/V, anorexia, flushed skin, tachycardia, restlessness, agitation, elevated body temp, muscle twitching, and HYPERTENSION--- what is the dx?

hypernatremia

What is the major intracellular cation that regulates activity at the neuromuscular junction, as well as cardiac muscle contraction and pH?

potassium (K+)

What is the normal range for potassium?

3.5-5.0

How is potassium regulated?

dietary intake and renal system

What are some medication causes for hyperkalemia?

▪ACE Inhibitors (lisinopril)

▪Potassium-sparing diuretics (spironolactone)

▪NSAID's (ibuprofen)

▪Beta blockers (metoprolol, labetalol, etc)

▪Trimethoprim (antibiotic)

What is a major extracellular anion that helps maintain osmotic pressure and keeps the body hydrated via electric neutrality with Na+ and CO2 interactions?

chloride (Cl-)

What a byproduct of the bodys metabolism which is brought to the lungs by the blood converted to CO2 and excreted and reabsorbed by the kidneys?

Bicarbonate (HCO3-)

What is the term for ions capable of carrying electric charge?

elecrolytes

What are the cation electrolytes (positively charged)?

▪Sodium (Na+)

▪Potassium (K+)

▪Calcium (Ca++)

▪Magnesium (Mg++)

What are the anion electrolytes (negatively charged)?

▪Chloride (Cl-)

▪Bicarbonate (HCO3-)

What is typically reported in the BMP or CMP and used to determine the cause of metabolic acidosis?

anion gap

What is the formula for anion gap?

([Na+] + [K+]) - ([Cl-] + [HCO3-])

cations- anions

What is an extracellular anion that has half forms exist as free and other half as protein bound-- and is used to evaluate parathyroid function?

Calcium (Ca2+)

What ion is used to evaluate parathyroid function, neural synapse and contraction of muscles, and proper bone formation?

calcium

There is a _____ relationship between calcium and phosphate which is regulated by PTH.

inverse

Are these causes of elevated or decreased Ca2+?

▪Hyperparathyroidism

▪Malignancy (e.g., SCC, renal, ovarian, endometrial, breast, lymphoma)

▪Multiple myeloma- (CRAB)

Sarcoidosis

hypercalcemia

Are these causes of elevated or decreased Ca2+?

▪Renal failure

▪Hypoparathyroidism

▪Vitamin D deficiency / osteomalacia

hypocalcemia

What is the required testing/results for a pt to be diagnosed with CHRONIC renal failure?

at least 2 abnormal albumin/creatinine ratio tests over 3 or more months*