Professional Refresher: Biochemical Assessment
Electrolytes
Electrolytes are assessed via blood tests.
Electrolyte
Normal Range
Implications if Low
Bicarbonate
23-32 mmol/L
Acid/base imbalance;
dehydration or overhydration;
uncontrolled diabetes, kidney
disorders, hyperventilation
Calcium
8.4-10.2 mEq/dL
Hypoparathyroidism,
(serum)
kidney/liver disorders,
magnesium deficiencies,
osteomalacia, pancreatitis,
vitamin D deficiency
Chloride
98-108 mmol/L
Chronic lung disease,
prolonged vomiting/sweating,
metabolic acidosis,
adrenal/kidney disorders
Magnesium
1.7-2.2 mg/dL
Irregular heart rhythms;
alcoholism, hemodialysis,
pancreatitis, too much insulin,
cirrhosis
Phosphate
2.4-4.1 mg/dL
Alcoholism, hypercalcemia,
hyperparathyroidism, rickets,
osteomalacia
Potassium
3.5-5 mEq/L
Cardiac arrhythmias, kidney
disorders, diarrhea, eating
disorders, heavy sweating,
vomiting
Sodium
136-145 mg/dL
Kidney/adrenal issues,
diarrhea, diuretics,
dehydration, ketonuria
Implications if High
Acid/base imbalance; dehydration
or overhydration
Hyperparathyroidism,
hyperthyroidism
Kidney issues, dehydration,
overactive parathyroid
Renal failure, dehydration, oliguria,
diabetic acidosis
Diabetic ketoacidosis,
hypoparathyroidism, liver disease,
renal failure, too much vitamin D
Cardiac arrhythmias, kidney issues
or drugs that decrease K+ excretion
Kidney issues, hyperaldosteronism
Fluid
Dehydration assessment and causes
Any of the following physical findings may be a result of any of the following etiologies of dehydration.
Physical findings:
 Dark-colored urine
 Dry mucous membranes
 Poor skin turgor
 Sunken eyes
 Sunken veins
 Thirst
 Weight loss
Possible etiologies:
 Anabolism
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Burns
Diarrhea
Drainage
Fever
Inadequate fluid intake
Medication
Open wounds/sores
Sweating
Vomiting
Overhydration assessment and causes
Any of the following physical findings may be a result of any of the following etiologies of overhydration.
Physical findings:
 Edema or fluid retention
 Light-colored urine
 Moist skin
 Shortness of breath; lung crackles
 Vein distention, especially jugular vein
 Weight gain
Possible etiologies:
 Antidiuretic hormone imbalance
 Excessive fluid intake or administration (through IV, feeding tube, surgical procedures)
 Hypertension
 Renal, liver, or congestive heart failure
Lab
Normal Range
Trend for Dehydration
Albumin
3.5-5 g/dL
BUN
BUN/creatinine ratio
Creatinine
Hematocrit
7-20 mg/dL
6-25
0.6-1.2 mg/dL
36-45% females
38-50% males
12-16 mg/dL females
14-18 mg/dL males
285-295 mOsm/kg
135-145 mEq/L
200-400 mg/dL
NA
Increased
(hemoconcentration)
Increased
Increased (15-20:1)
Increased
Increased
Hemoglobin
Osmolarity
Sodium
Transferrin
Weight
Increased
Trend for
Overhydration
Decreased
NA
NA
NA
NA
NA
Increased
Decreased
Increased
Decreased
Increased
Decreased
Decreased ( unless
Increased
masked by edema)
*Lab values need to be put into overall context of patient as abnormalities can be caused by other factors
besides fluids.
Estimating total body water (TBW):
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Males, if < 80 years old: 0.6 x weight (kg)
Males, if > 80 years old: 0.5 x weight (kg)
Females, if < 80 years old: 0.5 x weight (kg)
Females, if > 80 years old: 0.4 x weight (kg)
If obese patient, then subtract 10% after algorithm
Estimating fluid deficit-fluids should be replaced slowly, with half of deficit given over first 24 hours:
Water deficit (liters) = {TBW x [(actual sodium – desired sodium) / desired sodium]}
Renal function

Biomarkers for renal function
o Creatinine clearance or GFR
o Increased creatinine and BUN
 Indicates levels of uremic toxins
o Blood glucose
 High blood sugar leads to kidney damage
o Electrolytes
 Kidneys are responsible for filtering them, so if high, then could point to kidney damage.
o Urinalysis
 Presence of:
 Albumin/protein
 Blood
 Ketones
 Glucose
 White or red blood cells
o Anemia can develop if kidney does not make enough erythropoietin, which makes RBCs
 Biomarkers for anemia
 Hematocrit and hemoglobin
 Serum ferritin
 Iron studies
Cardiac function

Biomarkers for cardiac function
o Cardiac troponins
 Biomarker of choice for cardiac injuries
o Aspartate aminotransferase
o Lactate dehydrogenase
o Creatinine kinase
 Peak 12-24 hours after injury
 May rise in any skeletal muscle damage
o Myoglobin
 High sensitivity and released within 1 hour after injury
 May be released with any skeletal muscle injury
o CRP (inflammation marker)
o Cardiac natriuretic peptides (hormones made by heart)
 ANP
 BNP
o
o
o
o
o
 Normal = 0-99 pg/mL
 > 100 signals heart is working too hard
 > 900 = severe heart failure
High sodium, creatinine, and BUN are seen in HF
Triglycerides
Total cholesterol: > 200 mg/dL is bad
LDL: > 100 mg/dL is bad
 Apo B reflects LDL
HDL: < 35 mg/dL is bad
 Apo A reflects HDL
References and recommended readings
Family resource center. Illinois Council on Long Term Care website.
http://www.nursinghome.org/fam/fam_018.html. Accessed October 22, 2015.
Farinde A. Lab values, normal adult. Medscape website. http://emedicine.medscape.com/article/2172316overview. Updated May 14, 2014. Accessed October 22, 2015.
Forough R, Scarcello C, Perkins M. Cardiac biomarkers: a focus on cardiac regeneration. J Tehran Heart Cent.
2011;6(4):179-186.
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=3467959&tool=pmcentrez&rendertype=abstract.
Accessed October 22, 2015.
Huang LH, Ellsbury DL, George CS, Anchala KR. Dehydration. Medscape website.
http://emedicine.medscape.com/article/906999-overview. Updated September 25, 2014. Accessed October
22, 2015.
Kociol RD, Pang PS, Gheorghiade M, Fonarow GC, O’Connor CM, Felker GM. Troponin elevation in heart
failure: prevalence, mechanisms, and clinical implications. J Am Coll Cardiol. 2010;56(14):1071-1078.
doi:10.1016/j.jacc.2010.06.016.
Lerma E. Novel biomarkers of renal function. Medscape website.
http://emedicine.medscape.com/article/1925619-overview. Updated October 29, 2014. Accessed October 22,
2015.
Nelms M, Sucher KP, Lacey K, Roth LS. Nutrition Therapy and Pathophysiology. 2nd ed. Belmont, CA:
Brooks/Cole (Cengage Learning); 2011.
Contributed by: Alex Lewis, RD, LD
Review date: 9/28/15
Keywords: Biochemical assessment, nutrition labs, electrolytes, fluids, renal, cardiac