Dialysis Lab Values Question

  1. Hello!

    I'm in my last semester of RN school, and we recently had a rotation through dialysis. Unfortunately that rotation ultimately ended with nurses making students feel like we weren't wanted there, and some questions were never answered. The question i have been unable to get answered is: Relate the differences in the key lab values, pre and post dialysis.

    I'm guessing from what little i got from the mad-at-the-world-nurse, that the key lab values too look for are BUN, KT/V, creatinine, potassium, phosphorus, calcium, magnesium, RBC, Albumin, PTH, hemoglobin and hematocrit.

    My understanding is that POST dialysis, BUN, creatinine, Phosphorus, potassium, and magnesium would decrease. What do the RBC's, Albumin, PTH, H&H, Calcium look like POST? and Why/how does this relate to PRE-dialysis? What Does KT/V Measure?

    Thanks so much! I've looked all over for answers so any help is appreciated
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    Joined: Nov '08; Posts: 20; Likes: 2


  3. by   GeauxNursing
    Phosphorus is removed in very small quantities from dialysis alone. Patients take medicine to help their body move the phosphorus through the stool, rather than absorbing it. Phosphorus is in most everything! It's a constant struggle for them.

    KT/V measures the adequacy of the dialysis treatment. How well was the blood cleaned, basically. Pre- and post lab draw for comparison is necessary to run this test.

    Potassium is watched closely because a deviation outside the limits in either direction can cause dangerous dysrhythmias. We use dialysate baths that contain many electrolytes including K and Ca to try and maintain safe levels. More or less. (Bad description, I know. Sorry.)
    Albumin, if I'm not mistaken, is a very large molecule, so it does not normally "dialyze out," as we say in the biz : ) However, dialysis pts are notorious for having low albumins. Maybe someone else can explain why?
    H and H is measured weekly in the chronic HD units. Routine "dialysis" meds such as Epogen and iron are dosed to the pt based on H and Hs. Anemia is common in the dialysis population, so these patients get EPO on a regular basis. Normal people have hgb around 12-18, I believe. Dialysis patients should hover between 10-12ish.
    As a dialysis nurse, I have no idea what "normal" lab values are. : ) I only know dialysis pts. This may be a good time to go review. . .
  4. by   DeLana_RN
    I'm a former dialysis nurse and agree with pp. Maybe I can add a thing or two.

    Albumin is often low in this pt population because of their poor nutritional status; in acute (hospital based) dialysis we would often get orders to give a pt albumin.

    The reason that the dialysis pts' hgb is maintained at a relatively low value (the goal was 11-12 when I worked in a clinic) is that morbidity and mortality - for instance, from CVD - significantly increases if it's in a higher, more "normal" range.

    Basically, although chronic dialysis can do a pretty good job at keeping pts alive, it's not optimal (transplation is a much better option, but we know about the organ shortage). Once in ESRD/on dialysis, pts' average life expectancy is only about 5 years. And their fluid/electrolyte balance is always out of whack, especially close to the next treatment.

    The lab value we were most concerned about (especially in acute pts) was, of course, K+.


  5. by   Lacie
    Also renal failure pts dont produce erythopoetin which is required to produce new RBC's therefore hct/hgb is monitored so closely. Most require Epogen adjustments to maintain to stimulate the bone marrow to produce new RBC's. Ideally we like to keep them between 11-12. Also PTH (Parathyroid hormone) is monitored closely as if it increases signficantly then Calcium is pulled from the bone to the serum and becomes a vicious cycle. We usually give IV Zemplar and in turn have to closely monitor thier CA, PHo4, and CAxPHo4 levels to adjust it. In severe cases pts may need a parathyroidectomy. They also require phosphate binders to be taken with thier meals and snacks. Not before or after but it's important they take them directly with thier food. Another lab is Ferritin levels along with TSat to monitor Iron levels. Doses of iron can also assist in maintaining the desired levels of HCT/HGB therefore helping in keeping some of the epogen doses down. (Epo is extremely expensive and goverment monitored). Not only is KT/V monitored and guidelines per CMS is 1.2 generally we like to keep them above 1.4 with a URR above 65. Albumin levels should be a minium of 3.5 therefore once on dialysis we encourage high protein meals and may even require IDPN. Renal patients tend to loose protein as kidney have difficulty processing (pre renals usually have protein restrictions). Liver enzymes are also important to monitor. Some nephrologist wont freak at a higher level of K in renal pts whereas others will. All depends on the doc. Most case of increased K can be controlled by pt compliance with diet then you have those no matter what you do it can be difficult. Hope this helps some. Pretty much look back at your pathophysiology and consider what the kidneys function and control of other body functions do (hypertension, etc). Many dialysis pts still urinate just as well as any of us but are unable to filter waste therefore become uremic and esentially poisoning thier own systems. Of course these are more intended to the chronic renal dialysis patient.
    Last edit by Lacie on Oct 15, '09
  6. by   snowmaiden2005
    Thanks so much for your help! You were all life savers for my homework, and it all makes SO much more sense now