Chem 3 reference ranges

Sodium

136-145 mEq/L

Potassium

3.5-5.1 mEq/L

Chloride

98-107 mEq/L

pH

7.35-7.45

pCO2

35-45 mmHg

Bicarb (HCO3-)

23-29 mEq/L

BUN

6-20 mg/dL

Creatinine

Men: 0.9-1.5 mg/dL

Women: 0.8-1.2 mg/dL

Uric acid

Men: 4.0-8.5 mg/dL

Women: 2.7-7.3 mg/dL

Ammonia

14-45 umol/L

Osmolal gap

Normal: ~0.0 mOsm/kg

Clinically significant if value is > 10 mOsm/kg

Anion gap with K+

16 ± 4 mEq/L; 12-20 mEq/L

Anion gap without K+

12 ± 4 mEq/L; 8-16 mEq/L

Calcium

8.5-10.5 mg/dL

Magnesium

1.9-2.5 mg/dL

Inorganic phosphorus

2.5-4.5 mg/dL

Sodium cation/anion?

Major extracellular cation

Potassium cation/anion?

Major intracellular cation

Chloride cation/anion?

Major extracellular anion

Bicarbonate cation/anion?

Secondary extracellular anion

Magnesium cation/anion?

Secondary intracellular cation

Inorganic phosphorus cation/anion?

Major intracellular anion

Too much ADH

SIADH

Too little ADH

Diabetes Insipidus

Oliguria results in high urine osmolality

SIADH

Polyuria results in low urine osmolality

Diabetes Insipidus

Overhydration results in low plasma osmolality & hyponatremia

SIADH

Dehydration results in high plasma osmolality & hypernatremia

Diabetes Insipidus

What disorder cause patients to have excessive thirst?

SIADH and Diabetes Insipidus

Increased Plasma Osmolality

Excessive amounts of Glucose in plasma

Diabetes Mellitus

Increased Urine Osmolality

Glucose levels above renal thereshold

Diabetes Mellitus

Increased Osmol Gap

Ketoacidosis, increased unmeasured anions

Diabetes Mellitus

Polydipsia, Polyuria, Polyphagia & Unexplained weight loss

Diabetes Mellitus

Decreased renal perfusion pressure…

release of renin

Sympathetic nerve stimulation

release of renin

decreased sodium concentration in distal tubule fluid

release of renin

Renin travels from kidneys to _____ where Angiotensinogen is converted into ________

liver; Angiotensin I

Angiotensin I travels from the liver to the ______ where the angiotensin converting enzyme acts upon it to produce _______

lungs; Angiotensin II

____inhibitor drugs taken for high blood pressure prevent Angiotensin II from being produced and blocking the stimulus for vasoconstriction of blood vessels

ACE

1) Stimulates H2O ____ at Hypothalamus → result: ____

input; thirst

2) Stimulates H2O _____ at Hypothalamus causing the release of ______ → Result: _______

Output; Antidiuretic hormone (ADH); water retention

3) Causes the __________ of blood vessels → Result: ____

Vasoconstriction; increased blood pressure

4) Stimulates the adrenal cortex to release _____ → Result: ______

aldosterone; Distal convoluted tube reabsorb Na+ and secretes K+

Less Sodium reabsorbed at DCT

Less Potassium secreted at DCT

Hypoaldosteronism

Sodium reabsorbed at DCT

Potassium secreted at DCT

Aldosterone normal

More sodium reabsorbed at DCT

More potassium secreted at DCT

Hyperaldosteronism

H+ into cell

K+ out of cell

Lowers H+ in plasma

Acidosis:

Plasma more acidic

pH low

More H+

H+ out of the cell

K+ into cell

Raises H+ in plasma

Alkalosis:

Plasma more basic

pH High

Less H+

Cl- into cell

HCO3- out of cell

More HCO3- to bind free H+ so raises pH

Acidosis:

Plasma more acidic

pH low

More H+

Cl- out of cell

HCO3- into cell

Less HCO3- to bind free H+ so lowers pH

Alkalosis:

Plasma more basic

pH High

Less H+

Depletional

Dilutional

PseuDohyponatremia

Hyponatremia

Depletional hyponatremia

Renal losses: Diuretic use and hypoaldosteronism

Non-renal losses: GI loss (vomiting), skin loss (burns/trauma)

Dilutional hyponatremia

SIADH

Hyperglycemia

Pseudohyponatremia causes

Hyperlipidemia

Hyperproteinemia

Falsely low Na+ due to analytical errors

Water loss

Sodium gain

Hypernatremia

Causes of water loss hypernatremia

GI loss

Excessive sweating

Diabetes insipidus

Causes of Sodium Gain hypernatremia

ingestion or infusion of Na+

Hyperaldosteronism

Increased cellular uptake

Increased renal loss

Excessive GI loss

Hypokalemia

Renal loss causes hypokalemia

Hyperaldosteronism

Diuretic therapy

Licorice ingestion

GI loss hypokalemia

Vomiting

Diarrhea

Laxative abuse

causes of hyperkalemia

increased intake

increased cellular lysis

altered cellular uptake

impaired renal excretion

pseudohyperkalemia

increased intake causes hyperkalemia

transfusion of aged blood

supplementation (banana, meds)

increased in vivo cell lysis causes of hyperkalemia

cellular trauma

cellular injury

in vivo hemolysis

Altered cellular uptake causes hyperkalemia

compensation for acidosis (H+ taken into the cell; K+ put out of cell for electroneutrality)

insulin deficency

causes of renal excretion hyperkalemia

renal insufficiency or failure

hypoaldosteronism

GI losses

Burns

renal loss

Hypochloremia

general causes of hyperchloremia

dehydration

compensation for metabolic alkalosis

Causes of hypomagnesemia

impaired intake

excessive renal loss

causes of hypermagnesemia

renal failure

magnesium intoxication (milk of magnesia, antacids)

Treatment for toxemia of pregnancy

what causes tetany

hypomagnesemia

causes of hypocalcemia

decreased serum protein

hypoparathyroidism

steatorrhea

nephrosis

pancreatitis

Vitmain D deficiency

Heparin given during surgery

causes of hypercalcemia

Metastatic bone disease

hyperparathyroidism

multiple myeloma

causes of hypophosphatemia

rickets

hyperparathyroidism

fanconi syndrome

hemolytic anemia

diabetes mellitus

causes of hyperphosphatemia

glomerular renal failure

hypervitaminosis D

hypoparathyroidism

bone repair

Methods for sodium and potassium

atomic absorption spectroscopy

flame photometry

Potentiometry

Iontophoresis

sweat chloride → Cystic fibrosis

Historical method for calcium precipitation method

Clark and Collip method

precipitation with oxalate

dyes used for historical calcium method

o-cresolphthalein

arsenazo III

reagents used in photometric magnesium method

calmagite, formazan, methylthymol blue

reagent for phosphorus method

ammonium molybdate

causes of an increased anion gap

Increased unmeasured anions

• Lactic acidosis

• Ketoacidosis

• Toxic ingestion of methanol, ethylene glycol, salicylate

Decreased unmeasured cations

• decreased calcium

• decreased magnesium

Lab error

• overestimation of sodium

• underestimation of chloride or bicarb

Causes of a decreased anion gap

decreased unmeasured anions

• hypoalbuminemia

increased unmeasured cations

• increased K+

• increased Ca2+

• increased Mg2+

• presence of paraproteins

lab error

• underestimation of sodium

• overestimation of chloride or bicarb

increases BUN

febrile illness

corticosteroid or tetracycline therapy

large protein ingestion

GI bleed with blood absorption in gut

elevated thyroid hormone concentration

decrease BUN

low protein diet

increased androgens

growth hormone

pregnancy

Hyperuricemia causes (uric acid)

increased formation/intake

decreased excretion

increased formation/intake causes hyperuricemia

excess dietary purine intake (Gout)

increased nucleic acid turnover (chemo, cancer, trauma)

altered ATP metabolism (alcohol tox and tissue hypoxia)

preeclampsia

down syndrome

decreased excretion causes hyperuricemia

acute or chronic kidney disease

increased renal reabsorption or reduced secretion

lead poisoning

preeclampsia

prescence of orgnaic acids (lactate or acetoacetate)

causes increased ammonia

inherited urea cycle deficencies

advanced liver disease

Reye’s disease

hepatic encephalopathy

specific source of urea

detoxification of ammonia

dietary protein intake

specific source of creatinine

anhydride byproduct of muscle metabolism

specific source of uric acid

purine base metabolism

specific source of ammonia

deamination of amino acids

urea enzymatic methods and ammonia

Berthelot reaction: NH4+ + phenol and hypochlorite → indophenol using nitroprusside as a catalyst → blue product

Coupled enzymatic reaction: NH4+ with 2-oxoglutarate (measure absorbance at 340 nm NADH oxidized to NAD+)

urea chemical method

urea+ diacetyl → (heat) Diazine

thiosemicarbazide and ferric ions added for the color

creatinine method

Jaffe

creatinine + picrate ions under alkaline conditions to form red-orange complex (Janovski complex)

Fuller’s earth

uric acid scientist name

Carraway

oxidation and reduction of phosphotungstic acid to tungsten blue

Enzymatic method for uric acid

uricase → allantion

HPLC → high sensitivity/specificity, but very expensive

prerenal azotemia causes

congestive heart failure

shock

hemorrhage

dehydration

marked decrease in blood volume

renal causes azotemia

renal failure

postrenal azotemia cause

renal lithiasis

tumors of the bladder or prostate

severe infection in the urinary tract

OBSTRUCTION → increased urea in blood