Routine Blood and Urine Testing

Why get tested?
How often should I be tested?     
Who should do the testing?
What tests should be done?
Kidney function
Creatinine clearance
Uric acid
INR (Pro-time)
Digoxin (Lanoxin)
Liver function
Liver Tests

 Why Get Tested?

 How Often Should I Be Tested?

Some people with heart failure (CHFers) need very little blood testing, while others may require frequent checks. Here is a rough idea of what a CHFer might expect:

  1. every 90 to 120 days routinely
  2. whenever the dose of a drug changes, testing may be done more often for awhile
  3. if your CHF becomes unstable, testing should be done more often until you stabilize
  4. if you develop another serious illness, your testing may need to be more frequent
  5. whenever a drug is added to, or dropped from, your therapy, extra testing may be necessary for awhile

 Who Should Do The Testing?

Either your heart failure specialist or your PCP. If your PCP does it, he should talk to your CHF doc first to be sure he is running the proper tests and not missing any. You should confirm that he has talked to your CHF doc by talking with your CHF doc yourself. Never assume that everyone is on the ball.
     Whichever doc orders your testing from the lab will receive the lab results. He should then call you and let you know if the results are okay or not. Never assume that silence means good test results! If your PCP does it, he should also copy the results to your CHF doc. Again, confirm that this is being done by talking to your CHF doc yourself.

 What Tests Should Be Done Routinely?

When a doctor orders electrolyte testing - an electrolytes "panel" or "lytes panel" - he will always get at least carbon dioxide, chloride, potassium, and sodium measurements. Magnesium and calcium testing are usually ordered separately - and should be! These tests should be done routinely for most people with heart failure.
     When a doctor orders a "basic metabolic panel" or BMP, he will always get at least calcium, carbon dioxide, chloride, creatinine, glucose, potassium, sodium, and BUN measurements. This should be done routinely for most CHFers.

Routine tests for CHFers regardless of meds
Electrolytes Kidney function
Potassium BUN
Magnesium Creatinine
carbon dioxide  
Routine blood tests for CHFers taking these meds
Meds Test
   beta-blocker    Blood sugars
   digoxin (Lanoxin)    Dig level
   Coumadin (warfarin)    INR
   amiodarone (Cordarone)    liver function

You should have your electrolytes tested if you take diuretics, ACE inhibitors, or spironolactone (Aldactone), especially if changing dose; or if you add or drop any of these drugs. Normal ranges for electrolytes are:

Electrolyte Normal Results Range
potassium K 3.6 to 5.4 mEq/liter
magnesium Mg more than 1.7 mEq
sodium Na 136 to 143 mEq/liter
calcium 8.5 to 10.5 mg/dL
chloride Cl- 98 to 108 mmol/liter
carbon dioxide CO2 22 to 31 mmol/liter
Too much potassium
is called hyperkalemia. Signs of too-high potassium may include anxiety, irritability, stomach cramps, diarrhea, overall weakness, and muscle spasms. Your pulse may be slow and weak
Too little potassium
is called hypokalemia. Signs of too-low potassium may include sluggish thinking, very dry skin, depression, swollen abdomen, loss of appetite, edema, nervousness, irregular heart beat, muscle weakness, and headaches. Your pulse may be fast, then slow.

You should be tested for potassium level if you take diuretics, ACE inhibitors, or spironolactone (Aldactone). Potassium is an element - a substance that cannot be broken down into more basic substances. It is often just called "K" - its symbol in the Periodic Table of Elements.
     Nutritionally, potassium is a mineral. Potassium in our bodily fluids is an electrolyte. Electrolytes are substances that carry an electrical charge. They play a key role in maintaining fluid balance inside our bodies. A healthy human body is 50 to 75% fluid, so that's no small thing.
     Potassium helps conduct nerve impulses, control cells, and helps all kinds of muscle work properly. The body's fluid balance is controlled by exchanging potassium inside cells with sodium outside cells. This exchange helps maintain blood pressure, and helps make muscles contract - including your heart. The human body relies on proper potassium level to keep your heart beating! Standard values are:

If your potassium level is over 6 mEq/L, you may be in trouble
If your potassium level is under 2.8 mEq/L, you may be in trouble
Too much magnesium
is called hypermagnesemia. Aside from possibly causing diarrhea, I know of no ill effects from reasonable doses of oral magnesium. If you have kidney failure, take magnesium supplements only on your doctor's okay. Never take mega-doses of anything.
Too little magnesium
is called hypomagnesemia. Low magnesium levels can cause heart arrhythmia. Symptoms may also include weakness, tremors, twitching, a "crawling" sensation of the face, and convulsions. Hypomagnesemia is linked to diuretic use, low calcium level, low potassium level, long-term feeding by stomach tube, IV therapy, diabetes, thyroid trouble, dialysis, and pregnancy

You should be tested for magnesium level if you take diuretics, digoxin (Lanoxin), Quinidine, Procainamide, or Norpace. People taking digoxin should take 300mg magnesium daily.
     If you have chronic unexplained diarrhea, your magnesium level should be checked regularly. Unexplained lethargy and confusion are reasons to have your magnesium level checked. If you rely on a stomach tube for food, your magnesium should be checked every month. Magnesium is a mineral needed for your body to use ATP as an energy source. It is also necessary for blood clotting and muscle function.
     Most doctors know that if you take ACE inhibitors or diuretics, you need your potassium checked regularly. They don't usually think to check your magnesium, though.
     If you're low on magnesium, your bones give away part of their magnesium to the body's fluid to keep the blood level of magnesium up. This means that by the time your blood level drops, you're really low on magnesium in your body overall. It can then take up to 6 months to build your magnesium stores back up.

Less than 1.6 mEq/L is too low (hypomagnesia)
Magnesium is discussed here
Too-high blood sodium level
is called hypernatremia, and causes dehydration. It lowers the amount of water in the spaces between cells, which causes your brain cells to shrink (no kidding).
     Symptoms may include dry mouth, thirst, restlessness, irritability, disorientation, and fever. This is very dangerous. Hypernatremia often happens because the total amount of blood in your body is too low (hypovolemia). In that case, symptoms may also include tachycardia and too-low blood pressure
Too-low blood sodium level
is called hyponatremia. Thiazide diuretics can cause this in elderly CHFers. Symptoms may include altered personality, lethargy, and confusion. If blood sodium falls below 115 mEq/liter, symptoms may include stupor, convulsions, and coma. Brain swelling can occur

You should be tested for blood sodium level if you have heart failure. Sodium is the primary positively-charged ion in your body outside the cells (extracellular). It is crucial to proper muscle function and nerve impulses. In the blood, sodium is usually paired with chloride. A lot of your kidney function is based on the absorbing or eliminating of sodium. A condition called dilutional hyponatremia (DHN) may be seen with a low sodium and chloride level. DHN indicates end-stage heart disease. Standard values are:

  • Normal range = 136 to 143 mEq/liter
  • 150 to 170 mEq/liter is usually due to dehydration
  • Over 170 mEq/liter may be due to diabetes insipidus
If your blood sodium level is under 120 mEq/liter, you may be in trouble
If your blood sodium level is over 160 mEq/liter, you may be in trouble
Too-high calcium level
is called hypercalcemia. Symptoms may include emotional instability, confusion, delirium, psychosis, stupor, coma, weakness, and seizures. Heart rhythm may be affected
Too-low calcium level
is called hypocalcemia. Symptoms may include weakness, headaches, intestinal cramps, heart arrhythmia, anxiety, twitching and cramping in hands, feet, arms, and face. This can also be felt as a "crawling" sensation in the skin or numbness

You should be tested for calcium if you have heart failure, especially if you take diuretics. Calcium - called Ca - is needed for muscles to contract, nerves impulses to travel, hormones to release, and blood to clot. Calcium as an ion (electrolyte) is critical for signaling between cells.
     Calcium actually plays a role in the proper functioning of neurons that makes us able to learn new things. It also helps regulate a lot of enzymes. In skeletal muscle, calcium is what starts muscle contraction. It is required for your heart muscle to beat!
     About 99% of body calcium is in bone, with the other 1% "free". That 1% causes those functions described above to take place. Vitamin D and magnesium are both necessary for your body to use calcium properly. The lab will measure your total blood calcium level. Ionized calcium alone is very hard to measure so it is only checked in patients who absolutely must know. Ionized calcium is roughly half of total blood calcium. Standard values are:

If your total calcium level is under 6 mg/dL, you may be in trouble
If your total calcium level is over 12.9 mg/dL, you may be in trouble
Too-high chloride level
is called hyperchloremia. Too-high chloride may cause dehydration and is linked to acute kidney failure, diabetes insipidus, and prolonged diarrhea. Drugs that increase chloride include steroids, estrogens, thiazides, and triamterene
Too-low chloride level
is called hypochloremia. Too-low chloride symptoms may include heavy sweating and vomiting. Vomiting can lower your chloride level. Drugs that lower chloride level include bicarbonate, steroids, diuretics, laxatives, and theophylline

Chloride is the primary negatively charged ion in your body outside cells (extracellular). If your chloride level is off, it can throw off your sodium level, and as we have seen, that ain't good!

 Carbon Dioxide
Too-high carbon dioxide level
is called hypercapnia. Too-high carbon dioxide often results from too-high bicarbonate (another electrolyte). Diuretics (thiazides, ethacrynic acid, furosemide [Lasix], Demadex [torsemide] ), long-term steroid use, and overuse of laxatives may cause high bicarbonate level
Too-low carbon dioxide level
is called hypocapnia

Carbon dioxide is often referred to as CO2. CO2 is usually eliminated from your body as quickly as it is produced; it is transported in the blood by either dissolving into the blood or by binding to hemoglobin. Ninety percent of CO2 in the blood is transported as bicarbonate. The bicarbonate travels to your lungs, where it is converted back into carbon dioxide.
     This process makes up a buffer system - 45% of the body's total buffering ability - that helps control the acid/alkaline balance in your body. That's critical since a drastic change in your pH (acid balance) can kill you in minutes.
     CO2/bicarbonate testing is sometimes done by arterial blood gas testing (ouch!) rather than by routine electrolyte testing methods.

     Kidney Function

Our kidneys are two small fist-sized organs on each side of our spine. Kidneys are the body's main system for getting rid of wastes. they keep or eliminate substances depending on the body's current needs. Urine is formed in the kidneys, which can produce up to 25 liters of urine a day! More than a thousand liters of blood passes through our kidneys for every one liter of urine that is made.
     The kidneys are made up mostly of nephrons - about one million nephrons per kidney. Each nephron contains a filtering system known as a glomerulus; and a tube through which filtered fluid travels. Each glomerulus is a network of tiny blood vessels surrounded by a membrane called Bowman's capsule. Your kidneys contain 50 miles of nephron tubules!

 BUN (Blood Urea Nitrogen)
Too-high BUN level
is called azotemia. Heart failure patients often have high BUN due to low blood flow to their kidneys. High BUN can also be caused by heart attack, intestinal bleeding, feeding by stomach tube, dehydration, high stress, or kidney failure
Too-low BUN level
is seen in liver failure, malnutrition, and pregnancy; or when you drink waaay too many fluids or get too much IV fluid at Club Med

You should be tested for BUN if you have heart failure, or take diuretics or ACE inhibitors, especially if changing dose. Urea nitrogen is a waste product caused by the way our bodies use proteins. Urea is formed by the liver and carried by the blood to the kidneys to be eliminated. Because urea is eliminated by the kidneys, measuring how much urea remains in the blood is one way to check kidney function - thus the BUN test.
     BUN can go up if you get too "dried out" from high diuretic doses, because then you don't have enough fluid inside you to properly get rid of waste products. Low blood flow from heart failure, and ACE inhibitor and beta-blocker use are two other reasons BUN goes up.
     Keep in mind that many things can cause BUN changes, so creatinine is considered a more precise way to test kidney funtion. Normal range for BUN is:

  • Men: 8 to 22 mg/dl
  • Women: slightly lower values than men
  • Pregnant women: values go down by about 25%
  • Elderly people: values may be a little higher
If your BUN reaches 100 mg/dl, you may be in trouble

You should be tested for creatinine if you take an ACE inhibitor, beta-blocker, diuretic, or spironolactone (Aldactone). Measuring serum creatinine can spot kidney trouble. Creatinine is the waste product of creatine phosphate, which is found in skeletal muscle. As long as your muscle mass is pretty constant, your creatine level should be constant. Creatinine is eliminated only through the kidneys so when kidneys get weak, creatinine level goes up.
     Normal creatinine range is:

  • Adult men: 0.6 to 1.3 mg/dl
  • Adult women: slightly lower than men due to less muscle mass
  • Children: 0.2 to 1.0 mg/dl
If your serum creatinine reaches 8 mg/dl, you may be in trouble

Smaller people will have lower levels since creatinine level is related to muscle mass. Serum creatinine is not changed by protein use or fluid intake. Creatinine levels rise and fall more slowly than BUN, so creatinine levels are a better way to check kidney function long-term.
     Tests to measure serum creatinine, urine creatinine, and creatinine clearance are all used to test kidney function. Serum creatinine does not go up unless at least 50% of the kidney's nephrons are damaged. Creatinine level relates to the kidneys' loss of nephrons like this:

Creatinine levels versus kidney damage
Creatinine level Kidney's approximate nephron loss
0.6 to 1.5 mgup to 50% nephron loss possible
1.6 to 4.6 mgover 50% nephron loss possible
4.7 to 9.9 mgup to 75% nephron loss possible
over 10 mg90% nephron loss possible, end-stage kidney disease
 Creatinine Clearance

This is not a routine test - A creatinine clearance test compares serum creatinine to the amount of creatinine eliminated in urine during a given time period, usually 24 hours. To start this test, you empty your bladder and flush it. Then you get to collect all your urine during the next 24 hours - nothing like carrying around a bucket full of pee to further your social life, huh? <g> During the test period, one blood sample will be taken to measure serum creatinine. Then they can compare the amount in your blood to the amount passed in your urine.
     Standard values are:

  • Adult men: 85 to 135 ml/minute
  • Adult women: 80 to 120 ml/minute
  • Pregnant women: 150 to 200 ml/minute
  • Elderly: values go down about 10% per decade after age 50
If your creatinine clearance approaches 10 ml/minute, dialysis may be necessary
Too-high osmolality
is called hyperosmolality. Extremely high osmolality can case stupor, seizures or death
Too-low osmolality
is called hypoosmolality

 This is not a routine test  - This test measures your body's ability to maintain normal fluid balance - amount of solids per unit of fluid. High osmolality is often seen in heart failure patients.
     In severe dehydration, osmolality will be high because there is less water in proportion to the solids in your blood. Urine osmolality measures how concentrated your urine is. Urine osmolality can be compared to serum osmolality for a good overall picture of your fluid balance. Sodium, blood urea nitrogen, and blood glucose (sugar) levels are important to your serum osmolality.
     Osmolality is measured as "so many" milliosmoles per kilogram of water: mOsm/kg.
     Standard values are:

  • Serum osmolality: 280 to 300 mOsm/kg water
  • Urine osmolality: 500 to 800 mOsm/kg water is usual, 50 to 1300 mOsm/kg water is okay
If your serum osmolality is less than 240, you may be in trouble.
If your serum osmolality is over 321 mOsm, you may be in trouble.
Serum osmolality over 384 mOsm causes stupor.
Over 400 mOsm may cause seizures.
Over 420 mOsm is fatal
 Serum Uric Acid
Too-high uric acid
is called hyperuricemia. Gout may result from uric acid crystals forming in your joints
Too-low uric acid
is called hypouricemia. Steroids, high dose aspirin, dye used in x-ray tests, and diabetes can cause hypouricemia

 This is not a routine test  - If you take long-term. high-dose diuretics, you may need this test done. Uric acid is the end product of purine metabolism. Purines are hard to explain in plain English so I'm not going to try. I'll just say that purines largely come from food and from the breakdown of proteins.
     Your kidneys get rid of about 2/3 of the uric acid your body produces each day; The remaining 1/3 is eliminated through the stool. Uric acid level may go up and down a lot and the "normal" range is very wide. That's why several uric acid tests may be ordered over a period of time to check it. High uric acid level may be linked to gout, kidney disease, alcoholism, dehydration, or anemia.
     Standard values are:

  • Men: 2.5 to 8 mg/dl
  • Men over age 40: 2 to 8.5 mg/dl
  • Women: 2.2 to 6.4 mg/dl
  • Women over age 40: 2.2 to 7.8 mg/dl
  • Boys: 3.6 to 5.5 mg/dl
  • Girls: 3.6 to 4 mg/dl
  • Urinary uric acid is between 225 to 750 mg over 24 hours
 If You Take Coumadin (warfarin)    

INR is a measure of how quickly your blood clots (coagulates). Some people say it measures how "thin" your blood is. A usual target INR is 2 to 3. This used to be measured as Pro-time (PT or PTT). Foods high in vitamin K change INR so have a talk with your doctor about diet if you take Coumadin. Some drugs like aspirin, amiodarone (Cordarone) and certain antibiotics can raise INR in people taking Coumadin as well. Beware taking Tylenol (acetaminophen) while on Coumadin.

     If You Take Digoxin (Lanoxin)
Too-high digoxin
Symptoms may include headache, fatigue, weakness, confusion, nausea, vomiting, diarrhea, loss of appetite, eyes becoming sensitive to light, blurred vision, colored halos in field of vision, hyperkalemia or hypokalemia, or heart rhythm disturbances. As many as 1 in 5 patients have too-high digoxin levels at least once
Too-low digoxin
the drug does you no good and you don't feel any better <g>

The normal range for digoxin level is 0.7 to 2 micrograms/ml. Generally speaking, you must take your digoxin dose 6 hours before having blood drawn to check your digoxin level. It also pays to keep in mind that a "normal" digoxin level can cause problems for some people with heart failure. That's another reason that it really pays to be treated by a CHF specialist.
     It takes about 5 days for digoxin to reach a new steady state after a change in dose. So after a dose change, dig level should not be checked for at least several days.

If your serum digoxin level is over 2.4 micrograms/ml, you may have a problem
     If You Take A Beta-blocker
Too-high blood glucose
is called hyperglycemia
Too-low blood glucose
is called hypoglycemia

Beta-blockers raise your blood sugar. This can heavily impact your life, especially if you are diabetic or borderline diabetic. This is not a "glucose tolerance test" where you have to fast for a certain number of hours before testing! If your blood glucose (plasma glucose) test is abnormally high, your doctor may want you to take the fasting test, though.

If your blood glucose level is under 45 mg/dL, you may have a problem
If your blood glucose level is over 500 mg/dL, you may have a problem
 Liver Function

The liver is the largest human internal organ. It is located just under your diaphragm in the upper right part of your abdominal cavity. The liver is divided into a right and left lobe, separated by a ligament. The right lobe is much bigger. The liver's working cells are called hepatocytes and anything liver-related is called hepatic.
     Since hepatocytes can actually repair and reproduce themselves, the liver is the only organ that can regrow part of itself after injury or removal. Your liver does a lot of work, but I am not getting into that because frankly, scientist types and doctors still don't really know what all the liver does.

Your gallbladder is closely linked to your liver and is snuggled up right underneath the liver's right lobe. The gallbladder stores and concentrates bile, which is made of bile salts, bilirubin, phospholipids, cholesterol, bicarbonate and water. Bile salts help fat be absorbed into your intestines. Bilirubin, cholesterol, and phospholipids are caused by the body's never ending cycle of breaking down food for energy. Bicarbonate and water help neutralize stomach acid in your intestine.

Liver tests
LFT (Liver Function Test) Normal Range
Albumin (serum)3.4 to 5 grams/dl
Total serum bilirubin0.1 to 1.3 mg/dl
Direct (conjugated)) bilirubin [Adult only]0.0 to 0.3mg/dl
Indirect (unconjugated) bilirubin [Adult only]Total bilirubin minus direct bilirubin
AST (Aspartate aminotransferase) [Adult only]5 to 38 IU/liter
ALT (Alanine aminotransferase) [Adult only]7 to 50 IU/liter
ALP (Alkaline phosphatase) [Adult only]30 to 130 ImU/ml
GGT (Gamma-glutamyltransferase)Men = 15 to 70 U/liter
Women = 5 to 45 U/liter
Total serum protein [Adult only]6 to 8.2 grams/dl

Albumin is only created in the liver and is the main protein in your blood. It helps keep oncotic pressure high, which prevents fluid from leaking out of blood vessels into the spaces between cells - which we CHFers know all too well as edema.
     Albumin also attaches to substances in the blood such as drugs and hormones, and carries them to your liver. Once the drug or hormone gets to the liver, it is separated from the albumin and cleaned out of the body. A high albumin level means you are dehydrated.


Bilirubin is a waste product created by the breakdown of heme in red blood cells. Blood level of bilirubin is considered a true test of liver function. It is often high in CHFers. Captopril, allopurinol (gout medicine), procainamide, and some antibiotics can raise bilirubin levels. Levels over 3 mg/dl can cause jaundice (jaundice is the yellow coloring of your skin from too much bilirubin). Bilirubin production and elimination go like this:

  1. Red blood cells are broken down and free bilirubin is carried in the blood by albumin to your liver. This is called "indirect" or "unconjugated" bilirubin. The normal range for indirect bilirubin is 0.1 to one mg/dl.
  2. The liver converts ("conjugates") bilirubin and makes it water dissolvable. This is called "direct" or "conjugated" bilirubin. The normal range for direct bilirubin is 0 to 0.3 mg/dl.
  3. Direct bilirubin is sent by way of bile salts to your intestine. Bacteria in the intestine break it down into urobilinogen and it is then eliminated via urine and stools.
     ALT  and  AST

ALT (Alanine aminotransferase) and AST(Aspartate aminotransferase) are liver enzymes that leak into the blood when liver cells are injured. These two enzymes used to be called SGPT and SGOT. They may be called by either name on lab test results.
     ALT and AST are found mainly in the liver and heart, with smaller amounts in the kidneys and skeletal muscles. Injury to the heart muscle or liver can raise AST level, so ALT is a better marker of liver problems. Getting an injection in your muscle (hip or arm) can release AST and ALT into the bloodstream, so don't get an injection before having these levels checked.
     Heart-related drugs that may affect ALT and AST include hydralazine, captopril, lovastatin, niacin, procainamide, amiodarone (Cordarone), and some antibiotics. If these enzymes are high, you may experience fever, weight loss, fatigue, nausea, or vomiting.


ALP (alkaline phosphatase) is found in the kidneys, bone, and intestine. ALP level is important for spotting liver and bone disorders. ALP is often high in CHFers.


GGT (gamma glutamyl transpeptidase) is an enzyme produced in the bile ducts. GGT measurement is a very sensitive test for liver dysfunction. Drinking alcohol raises GGT and the test detects even a tiny amount of alcohol in your system. GGT is often used as a way to be sure that high ALP is due to a liver problem.

All information on this site is opinion only. All concepts, explanations, trials, and studies have been re-written in plain English and may contain errors. I am not a doctor. Use the reference information at the end of each article to search MedLine for more complete and accurate information. All original copyrights apply. No information on this page should be used by any person to affect their medical, legal, educational, social, or psychological treatment in any way. I am not a doctor. This web site and all its pages, graphics, and content copyright © 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007 Jon C.

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