More Labs that you should know
Urine Specific Gravity
Clear Urine = Low Specific Gravity
Dark Urine = High Specific Gravity
- Let’s use Diabetes Insipidus and Syndrome of Inappropriate AndiDiuretic Hormone to learn about urine specific gravity.
- Normal= 1.010- 1.030
- < 1.010 urine is very dilute, very clear (e.g., DI)
- > 1.030 urine is very concentrated, very dark (e.g., SIADH).
- Did you know that the specific gravity of water = 1.0?
- Now let’s think in terms of hydrated and dehydrated. If you are dehydrated, your urine will be concentrated or have a high specific gravity (be dark). If you are well-hydrated, you urine will be clear or have a low or normal specific gravity.
Albumin
- Normal 3.4- 5 g/dL
- Indicator of nutrition, nutrition, nutrition.
- It is a large protein that keeps water in the vessels.
- Clients with ascites likely have low albumin; that is, why ascites fluid forms. There is not enough albumin to attract/keep fluid in the vessels.
- The pressure that keeps fluid in the vessels is called plasma oncotic pressure.
- Swelling/edema forms due to decreased oncotic pressure (low albumin).
- Why is a client swollen/edematous? Decreased oncotic pressure, low albumin level (also low protein levels).
Cardiac Enzymes
- Cardiac anzymes are released in response to cardiac ischemia/infarction. They include CK-MD, myoglobin, Troponin T, and Troponin I.
- Troponin I and T = Myocardial Infarction= MOST SPECIFIC to the heart
- If troponin is elevated always think MI, MI, MI, MI
- Look at the table below and notice that Troponin stays elevated the longest.
- Takes a few hours for enzymes to go up. To diagnose a myocardial infarction, SERIAL ENZYMES are ordered. Cardiac enzymes are usually ordered every 8 hours x 3.
| Enzyme | Indication | Initial Rise | Peak | Back to Normal | Normal Value |
|---|---|---|---|---|---|
| Troponin | Hgh Affinity for myocardial injury | < 4 hours | 12 hours | Up to 10 days | < 0.6 mg/mL |
| CK-MD (Creatine kinase, myocardial muscle) | Myocardial Injury | 4 to 6 hours | 18 to 24 hours | 72 to 96 hours (3 to 4 days) | 0% to 5% of Total = 26 to 174 units/L |
| LDH (Lactate dehydrogenase) | Two types LDH₁ and LDH₂. Usually 1<2, but if 1>2, it indicates myocardial necrosis. Basic math, right? | 24 to 48 hours | 2-3 days | 4 to 5 days | 140 to 280 IU/L. Look for the flipped values 1>2 |
| Myoglobin | Less specific since it is found in both skeletal and cardiac muscle | < 2 hours | 8 to 10 hours | 24 hours | 25 to 72 ng/mL |
BNP = Brain Natriuretic Peptide
- > 100 pg/mL = heart failure
- A hormone secreted by cardiomyocytes in the heart ventricles in response to stretching caused by ⇑ ventricular blood volume.
- ⇑BNP = ⇑ stretch = lots of fluid = the heart cannot pump adequately to move fluid around
Cholesterol and friends
- HDL normal value > 40 – 60 mg/dl. It is the good one. High Density Lipoprotein. High is good
- LDL < 130 mg/dl. It is the bad one. Low Density Lipoprotein. Low is good
- Triglycerides <150 mg/dl
- Cholesterol level < 200 mg/dl
- Normal values will be given to you on the NCLEX. Yaaay!
AST & ALT = The Liver
AST & ALT = 8 – 20 U/L. These values indicate how the liver is functioning. If they are elevated, be aware of medications metabolized by the liver. The NCLEX likes to ask: The client has these labs (elevated AST/ALT) which medication should you question? It is usually the antibiotics or the cholesterol medications.
The Diabetes Labs
- Normal Hemoglobin A1C 4-6 %
- A1C > 6.5 % = Diabetes
- Fasting blood sugar = 70- 110 mg/dl
- Fasting blood sugar for pregnant women < 95 md/dl
- Glucose Tolerance test is performed at 24 weeks of pregnancy.
- 1 hour if > 140 more testing needed
- 3 hour: 2 or more levels exceeded = diabetes
- fasting: < 95 mg/dl
- 1 hour: <180 mg/dl
- 2 hour: < 155 mg/dl
- 3 hour: < 140 mg/dl
- What does it mean? if at 3 hours, two of the blood sugars (fasting, 1-hr, 2-hr, and 3-hr) are abnormal, the client has pregnancy-induced diabetes.
PSA (Prostate Specific Antigen)
- < 0.4 ng/mL
- Draw levels 48 hours after digital exam because exam increases levels due to manipulation
- Saw Palmetto artificially decreases PSA Levels
- Levels recommeded for ages 55 and up, but younger clients may be tested if they have a family history.