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(value range)

8-20 mg/dL


Why would BUN be ordered for a patient?

To determine metabolic function of the liver and excretory function of the kidneys. Nearly all renal diseases are a result of inadequate excretion of urea from the kidneys.


What is BUN testing?

High BUN --> Kidney

Low BUN --> Liver

BUN is testing the amount of urea nitrogen in the blood.
Urea is the byproduct of protein metabolism in the liver.
During ingestion, proteins are broken down into amino acids and from amino acids to free ammonia in the liver. Ammonia is combined to form urea and transported to the kidneys for excretion.


S/S for High Value (BUN)
S/S for Low Value (BUN)

High Value:
- fatigue
- lack of concentration
- edema around the eyes, face, wrists, abd, thighs, ankles
- foamy urine
- reduced amount of urine
- flank pain
- high BP

Low Value:
- jaundice (eyes and skin)
- nausea, loss of appetite
- abd pain
- swelling of the abd, legs
- flu like symptoms (malaise)
- R abd pain


(value range)

0.7-1.3 mg/dL male
0.5-1.1 female

*critical value is > 4


Why would creatinine be ordered for a patient?

To determine renal function and GFR. Creat takes longer to elevate so we know elevated levels indicate a chronic problem.


What is creatinine testing?

It's testing the amount of creat in the blood. Creat is a catabolic product of creatinine phosphate, which is used in skeletal mm. contraction. Creat. is excreted by the kidneys and is directly proportional to renal function.


S/S for a High Value (creat)
S/S for a Low Value (creat)

High Value:
- fatigue
- lack of concentration
- edema around the eyes, face, wrists, abd, thighs, ankles
- foamy urine
- reduced amount of urine
- flank pain
- high BP
- itching

Low Value: usually caused by low mm. mass
- mm. weakness
- mm. pain
- reduced mobility
- mm. stiffness
- Liver problems (abd pain, swelling, jaundice)
- excess water loss (dehydration, poor skin turgor)

(JAMS = jaundice, abnormal pain/swelling, mm weakness, stools are tar/bloody/pale)


K+ (value range)

3.5-5 mEq/L
< 2. 5 and > 6.5 critical


Why would K+ be ordered for a patient?

K+ would be ordered for a patient to determine high or low levels. If we wanted to see water and electrolyte balance in the body, we test potassium. If we want to determine how the muscles and nerves are functioning, we test potassium. MINOR changes have significant consequences so we want to make sure we rule this out in patients! We don't want heart arrhythmias.

*also if on digoxin and diuretics (both issues if low values)


What is K+ testing?

K+ is testing the amount of potassium in the blood. Know that aldosterone increases renal loss of K+...this could rule out corticosteroid problems whether it's high or low. K+ is lost in sodium reabsorption. K+ is lowered in Alkalotic states and higher in Acidic states.


S/S for High Value (K+)
S/S/ for Low Value (K+)

*watch a video on this*

Hyper = Body CARED too much for K+

Cellular movement of K+ outside (burns, acidosis)
Adrenal insufficiency (Addisons)
Renal Failure
Excessive K+ intake
Drugs (K+ sparing diuretics, NSAIDS, ACE inhib)

Hypo: Body is trying to DITCH K+

Drugs (diuretics, laxatives, corticosteroids)
Inadequate intake of K+
Too much water intake
Cushings syndrome (too much aldosterone)
Heavy fluid loss (NG suction, vomiting, diarrhea, wound vac, sweating)

*hyper insulin, alkalosis


M - mm. weakness
U - urine oliguria/anuria
R - respiratory failure (mm. weakness, seizures)
D - decreased cardiac contractility (low BP, weak pulse)
Early signs of mm. twitching (late sign is profound weakness)
R - rhythm changes (peaked T waves, wide QRS, flat p waves)

- weak pulse
- decreased bowel sounds
- decreased DTR's
- flaccid paralysis (late sign)
- confusion
- weakness
- shallow respirations and diminished breath sounds
- EKG changes (prominent U waves, depressed ST segment, inverted T wave)
(everything is low and slow)

6Ls for Low

- Lethargy
- Lethal cardiac arrythmia
- Leg cramps
- Limp mm.
- Low shallow respirations
- Less stool


Sodium (value range)

135-145 mEq/L
critical values <120 and > 160


Why would sodium be ordered for a patient?

Sodium would be ordered to determine the balance between Na intake and Na output through kidney excretion. Water and sodium are very closely interrelated. As water in the body increases, sodium levels decrease and visa versa.

(fluid balances)


What is sodium testing?

Sodium is testing the amount in the blood. Sodium determines extracellular osmolality. Sodium balance in the blood determines balance between intake and renal excretion.


S/S for High Value (Na)
S/S for Low Value (Na)


F - fever/flushed skin
R - restlessness
I - increased BP and fluid retention
E - edema, extremely confused
D - decreased UO and dry mouth

S- seizures, stupor
A- abdominal cramping, attitude changes (confusion)
L - loss of urine and appetite
T - tendon reflexes diminished, trouble concentrating

L- lethargic
O- orthostatic hypotension, overactive bowel sounds
S- shallow respirations
S- spasms of mm.


Calcium (value range)

9-10.5 mg/dL


Why would calcium be ordered for a patient?

Calcium affects kidneys because of Phosphorus. Phosphorus is excreted mainly by the kidneys. Calcium and Phosphorus have an inverse relationship. Calcium binds to phosphorus to compensate for high phosphorus. You're body can't have both it takes one or the other.

To evaluate parathyroid function and calcium metabolism.
We typically look for these levels when monitoring patients with renal failure, renal transplantation, hyperparathyroidism. Also used to measure calcium levels during and after large volume blood transfusions (citrate in blood infusions binds to calcium).


What is calcium testing?

We are testing level of blood calcium since it affects mm. function, heart function, clotting, and teeth and bone formation. We also want to rule out malignancies like a tumor that could be causing elevated levels.


What are s/s of
Low Ca
High Ca

*note that albumin and calcium levels are directly proportional (low albumin = low calcium) they are usually bound together

Low Ca: usually result of malnutrition or large-volume IV infusions; others include intestinal malabsorption, renal failure, rhabdomyolysis, alkalosis, pancreatitis

Reflexes hyperactive
Arrhythmias (prolonged QT interval)
Mm. spasms in calves/feet (tetany/seizures)
Positive Trousseau's sign (tetany)
Sign of chvostek's sign (tapping of facial nerve to cause facial twitching)

High Ca: result of hyperparathyroid, tumor, immobilization, vitamin D toxicity, acromegaly, hyperthyroid

W - weakness of mm.
E - ekg changes shortened QT interval
A- absent reflexes/abdominal distension
K- kidney stone formation


Magnesium (value range)

1.5-2.4 mg/dL


Why would magnesium be ordered for a patient?

Know that it is bound to ATP so it's highly involved in all metabolic processes. We especially monitor magnesium levels in cardiac patients. It's hard to maintain K+ with low Mg levels.

Toxemia (pregnancy and low Mg levels)

Excreted by the kidneys exclusively


What is magnesium testing?

It's testing the amount of magnesium in the blood to determine whether it's causing cardiac irritability or arrhythmias. It slows neuromuscular conduction (with low Mg) and will demonstrate widened PR and QT intervals with wide QRS.


S/S for High and Low value of Magnesium

High Mg: causes include renal insufficiencies, uncontrolled DM, addison disease, hypothyroidism, ingestions of magnesium

Lethargy (profound)
EKG changes (long PR and wide QRS)
Tendon reflexes absent
Arrythmia (bradycardia, heart blocks)
Respiratory arrest
GI issues (N/V)
Impaired breathing (skeletal mm. issues)
Cardiac arrest

Low Mg: causes include malnutrition, malabsorption, hypoparathyroid, alcoholism, renal disease, diabetic acidosis

(body is hyperexcited opp. of hypermag)

T- trousseau's sign
W- weak respirations
I- irritable
T- torsades de pointes
C - cardiac changes (tall T waves, depressed ST) AND Chvostek's
H - hypertension/ hyper-reflexia
I - involuntary movements
N - nausea
G - GI probs (decreased bowel sounds)


Chloride (value ranges)

98-106 mEq/L


Why would chloride be ordered for a patient?

To determine electrolytes which affect acid base balance and hydrational status.


What is chloride testing?

Chloride maintains electrical neutrality. Chloride also determines hydration since water moves with sodium and chloride. Chloride serves as a buffer in acid base balances. Chloride shifts will also show a shift in bicarbonate.


S/S of High and Low value for Cl

High Cl: dehydration, excessive NS infusion, metabolic acidosis, hyperventilation, respiratory alkalosis

- lethargy
- weakness
- deep breathing
- hypertension

Low Cl: overhydration, SIADH, vomiting, chronic gastric suction, respiratory acidosis, burns, diuretic therapy

- hyperexcitability of nervous system and mm.
- shallow breathing
- hypotension
- tetany



Phosphate (value range)

3.0 - 4.5 mg/dL


Why would phosphate be ordered for a patient?

To determine calcium metabolism, parathyroid hormone, renal excretion, and intestinal absorption functions.