No! No! No! Never! Give a dialysis patient a Fleets Enema!

What is wrong with this picture?

Sevelamer and Fleet Enema. They go together like a honey baked ham and Chanukah. Fleets enemas have an obscene amount of phosphorous and sevelamer (Renvela) is a phosphorous binder. They should never co-mingle on the same MAR. So while some may see a couple of benign medications, I see a Chanukah ham.

A  Fleets enema, or any typical sodium phosphorous enema, is roughly 4 onces or 120 ml. The active ingredient is sodium phosphorous, to the tune of 26g of sodium phosphate per dose, some articles quote a phosphorous concentration of 13,000 mg/dL. Remember, a normal diet has about 1 gram of phosphate and only 700 mg of that is actually is absorbed; so we are talking about a potentially massive overdose.

I love that someone scanned the entire packaging

No patient with kidney disease or on dialysis should get this drug without talking to their doctor. Its written right on the damn package.

I guess, if you are in the hospital and the doctor orders it, that is essentially the same thing as asking your doctor. Too bad that over and over again doctors express their ignorance about dangerous this seemingly innocuous medication can be by ordering it in patients with kidney disease.

A rogues gallery of bad outcomes from the lowly Fleets Enema

The sodium phosphorous enema can be lethal to a patient with kidney failure.

Here is a case report regarding a patient who developed hypocalcemic tetany and coma following a single enema

My favorite quote in the case report is the hyperphosphatemia review of systems:

…the family denied that other drugs or unusual food such as star fruit was given by them- selves.

They gave the patient a couple of amps of calcium gluconate and then dialyzed him on hospital day 6, 7 and 8.

The situation is even more harrowing if you give the enema orally. This results in massive sodium and phosphorous absorption. In this case report the team gave it to the patient…twice:

They ran in to trouble while treating a toxic theophylline level. They gave activated charcoal to bind the theophylline. Subsequently, the patient developed an illeus and was given 120 mL of a sodium-phosphorous enema down the NG tube. The next day he received 4 liters of polyethylene glycol via the NG and finally another 120 ml sodium phosphorous enema enterally.

Then he arrested.

They resuscitated him. Here are his post-code labs:

  • Na 177
  • K 2.8
  • CO2 18
  • Cr 3.4
  • phosphate 59.6
  • calcium 5.2
  • Ca x Phos product: TFTC*
  • pH 7.12/37/40

* Too frightening to calculate

After resuscitation the patient was too hemodynamically unstable for dialysis and died during a subsequent arrest.

Look at that phosphorous! A phosphorous over fifty is like a traffic accident, can’t tear your eyes away.
Here’s a simple rule:

If the medicine is supposed to go in the butt, don’t feed it to your patient.

As high as the phosphorous is however, the symptoms are due to the low calcium. The high phosphorous complexes with the calcium driving the ionized calcium down.

JASN published a tight review in 1996. They discuss an unfortunate case where a gentleman was prescribed two enemas for a flexible sigmoidoscopy prep. The patient however, mistakenly ingested them orally rather than, you know, using them the right way. 191 mmol of sodium and 208 mmol of phosphorous down the hatch. The patient presented to the ER complaining of foot and hand pain along with diarrhea and difficulty swallowing and speaking. Data on presentation:

  • QTc 0.6 sec (prolonged)
  • ionized calcium 0.34 mmol/L
  • total calcium 4.5 mg/dL
  • Na 154 mmol/L
  • phosphate 44.8 mg/dl
  • anion gap 39

The patient was managed with insulin and dextrose, aluminum hydroxide and IV calcium gluconate along with IV fluids. Dialysis was delayed for 4 hours due to difficulty gaining IV access. He was dialyzed against a high (3.5 mg/dl) calcium bath

One of the points I tried to highlight in the graph is the rapid drop in the phosphorous prior to the dialysis. The conservative therapy of IV fluids, insulin, and aluminum hydroxide look highly effective. Also note how effective dialysis is at raising the calcium.

The authors make an excellent point regarding the acidosis. The patient had an initial pH of 7.28 and an anion gap of 39. The anion gap is from the high phosphorous. The authors point out that treating the acidosis with alkali will further drop the ionized calcium and is contraindicated until the calcium is corrected.

The discussion of the paper is delicious and addresses a situation I have found myself debating with fellows. The question is what to do when the phosphorous is really high and the patient has hypocalcemic symptoms. Does the administration of calcium lead to metastatic calcification to the detriment of the patient? The authors feel that calcium should be given to treat the symptoms of hypocalcemia and delay full treatment of hypocalcemia until the phosphorous is restored to normal levels.

In terms of personal experience, the MAR from the top of the post comes from a dialysis patient who did receive a Fleets enema while in the hospital. His phosphorous went from 3.5 to 11.7, overnight. He remained asymptomatic but the whole experience terrified me.

No. No. No Never. Give a fleets enema to a dialysis patient.

The agony and ecstasy of of secondary hyperparathyroidism

Managing secondary hyperparathyroidism in dialysis patients should be a rewarding aspect of nephrology. I thrive on complex management that involves balancing various numbers with clever treatment strategies. It is exactly what I find so exhilarating about a juicy electrolyte case in the ICU.

The principle variables in secondary hyperparathyroidism are:

  • PTH
  • Phosphorous
  • Calcium
And I use one additional lab that is generally ignored in the guidelines, alkaline phosphatase.
To bend these numbers we have a variety of tools with interesting effects, mechanisms of action and side-effects. The principle therapeutics:
  • low phosphorous diet
  • calcium containing binders
  • non-calcium binders
  • calcitriol
  • paricalcitol and doxercalciferol
  • cinacalcet
And additional therapeutics that can be brought to bear in difficult cases or in unusual circumstances
  • dialysate calcium concentration
  • parathyroidectomy

And K/DOQI provided cleanly laid out treatment goals:

  • PTH 150-300
  • Caclium 8.4-9.5
  • Phosphorous 3.5-5.5
  • Calcium x phosphorous product < 55
Patients that achieve those targets have a lower mortality risk than patients that miss these targets:

The numbers (0 of 3, 1 of 3, etc) refer to the number of months a patient is at the K/DOQI target in the quarter, PTH was measured only once a quarter

The problem is that no one has performed a prospective randomized controlled trial showing these targets improve outcomes. We want to believe that the retrospective data showing a survival advantage with cinacalcet and paricalcitol are real and that the observational data showing better calcium and phosphorous (and to a smaller degree, PTH) results in better patient outcomes.

Teng et al. Survival of patients undergoing hemodialysis with paricalcitol or calcitriol therapy. N Engl J Med (2003) vol. 349 (5) pp. 446-56

Block et al. Mineral metabolism, mortality, and morbidity in maintenance hemodialysis. J Am Soc Nephrol (2004) vol. 15 (8) pp. 2208-18
But given nephrology’s previous relationships with retrospective data (see anemia, Kt/V, and statins, and homocysteine) I can’t accept that data. I can’t take these treatment goals seriously. I appreciate that the fresh KDIGO guidelines readily admit that the emperor has no clothes and that the best they can recommend is to generally keep the calcium and phosphorous close to normal (evidence level 2D) and the PTH anywhere from 150 to 600 (evidence level 2c) or roughly wherever the hell you want it.

I love this figure from KDIGO, essentially once the PTH rises over 150 it provides no information. PTH > 300 has a positive predictive value of only 65% for high turnover disease. And don’t miss the laughably small numbers. We are basing global guidelines off of a study of less than 100 patients. From Barreto and Barreto.

It is shameful that Abbott has not done an RCT with survival as an endpoint on Zemplar or Calcijex. They have had 20+ years to do this. Both of the other players in CKD-MBD have taken a chance at building RCT data to support there products:

  • Genzyme took a poke with DCOR (RCT of sevelamer versus calcium based binders) 
  • Amgen is in the final countdown of EVOLVE (RCT of sensipar + usual care vs usual care)
Abbott the oldest player is sitting on the sidelines.
The lack of data, the lack of clarity, and the reliance on observational data muddles the issue enough that I don’t enjoy taking care of secondary hyperparathyroidism. But recently I had a great case, a situation where treating secondary hyperparathyroidism did more than loaded the dice in my patients favor but actually really made a difference.
I have a young dialysis patient who suffers from a horrific trauma a number of years ago. As a result he has profound chronic pain. Much of the pain is back pain but he also complained of diffuse body aches. Earlier this year his PTHs were consistently over a thousand with some over two thousand.
We added 90 mg of cinacalcet daily and the the PTH plummeted to goal. This was in a patient who had not responded to doxercalciferol 10 mcg three times a week. It was nice to see the PTH come down but what made this case standout was that his body aches melted away. We had been sending him to pain clinics and switching narcotics trying to get his pain tolerable and all of a sudden, done. Pain dramatically improved with a log reduction in PTH. 
Sometimes I get so carried away worrying about total mortality that I forget about the direct toxicity of high PTH. 

More on acetazolamide

A few weeks ago while on acetazolamide for altitude sickness prophylaxis the whole group noted tingling and paresthesias. What was curious is that the symptoms were most pronounced in the morning. The paresthesias were primarily on the hands and feet with a rare complaint of symptoms on the face.

I suspected that these symptoms are due to hyperventilation induced hypophosphatemia and the high carbohydrate breakfast (oatmeal) caused a bolus of insulin that further lowered the phosphorous. Does anyone know the etiology? Does hyperventilation cause hypophosphatemia if the increase in ventialtion is compensatory for metabolic acidosis?

FYI: the acetazolamide taste alteration makes carbonated beverages inedible.

Myles Wolf is coming to speak at Renal Grand Rounds today

Wolf has been everywhere and is one of the premiere scientists elucidating mineral metabolism. He was the senior author on the article in the NEJM on FGF-23 and dialysis survival and the recent article on the survival advantage with phosphorous binders.

Just a quick review of FGF-23 so I’m not an idiot when this rock star nephrologist starts talking. (FYI don’t let the clean cut pic above fool you, he came to the lecture in full rock-star fashion with the long hair, groupies (supplied by Genzyme) and everything)

FGF-23 is produced by osteocytes.

Klotho seems to be a required co-factor for FGF-23, such that mice that are Klotho deficient mimic the phenotype of FGF-23 deficiency.

FGF-23 increases renal phosphorous clearance by blocking Na-Phos reabsorbtion in the proximal tubule. FGF-23 also inhibits 1-alpha-hydroxylase, decreasing 1,25 OH-vitamin D.

Some of the biology is still a mystery. The highest density of fgf-23/klotho receptors are located in the distal tubule but the biologic effects stem from the proximal tubule.

FGF-receptor and Klotho are also found in the parathyroid gland but the exact role it plays is unclear. Some data points to direct stimulation of PTH and both molecules tend to rise together but this may be due to FGF-23 surpressing 1,25 OH D and secondary increases in PTH.

Increased phosphate and 1,25 vitamin D both stimulate the production of FGF-23. [Note Wolf provided data that phosphate levels do not increases FGF-23. He proposed that it is phosphate balance that is important, his supporting data included lupron treated patients bump their phosphorous by half a point but FGF-23 doesn’t budge, I couldn’t find this article on Google]. The Phex endopeptidase cleaves and inactivates FGF-23 so that is another control factor. [Wolf also discussed iron infusions causing phosphorous wasting due to excess FGF-23 ref pubmed related search]