Monday, October 27, 2008

Melamine in the eggs, melamine in pesticide

Hong Kong discovers high levels of melamine in chinese eggs:

Hong Kong said last week it would test meat, vegetables and processed food for melamine, a move that underlines concerns about food safety in the former British colony which returned to Chinese rule in 1997.

It imposed a cap on melamine in September, restricting it to no more than 2.5 milligrams per kilogram, while melamine found in food meant for children under three and lactating mothers should be no higher than one mg per kg.
The level of melamine found in the eggs was 4.7 mg per kg, the newspapers said.

The newest revelations on melamine toxicity involves vegetables that are sprayed with the insecticide cyromazine. This derivative of melamine degrades back into melamine resulting in the contamination.

Recently, experts have investigated and confirmed that melamine has also been found in lettuce, water cress, tomatoes, mushrooms, potatoes and other agricultural products. There is 17 milligrams (0.000037 lbs) of melamine per kilogram (2.20 lbs) of mushrooms.

Cyromazine itself apparently has very little toxicity:

Cyromazine is practically nontoxic (acutely) to mammals and birds. Exposure estimates for these organisms are 0.05 ppm. Acute toxicity for birds is 1785 ppm maximum. Safety factor is 105-106 for birds. Acute toxicity for mammals is 1000 ppm maximum. Safety factor is again 105 - 106.



Friday, October 24, 2008

How much bicarb is in baking soda

My fellow says there is 60 mEq in every tsp of baking soda.

That sounds like a lot.

Thursday, October 16, 2008

Important links

Abstracts from the NKF Spring Meeting 2008

Journal Club: Campath and ACE/ARB and AKI in CABG

The first article was an analysis of campath for induction with tacrolimus.
Patients were randomized to either
  • Methylpred 250 mg and Campath 20 mg immediately following surgery followed by Tacrolimus Group
  • Tacrolimus, prednisone, and MMF (no induction therapy)
Primary outcome was biopsy proven rejection at 6 months.
Secondary outcome was biopsy-proven rejection at 12 months, time to first rejection, patient and graft survival, incidence of corticosteroid resistant rejection.

n= 131 deceased donor, kidney transplant in patients with PRA ≤ 25%. All patients were receiving their first kidney. Age 18-65.

No episodes of humoral rejection was found in either group.

The figure above I think is particularly informative as it becomes obvious that all the difference is in the first month. This is a study of induction vs. no induction and they demonstrate a huge reduction in early rejection with induction.

Big picture: large reduction early reduction but no difference in serum creatinine at one year.
The second article was a retrospective analysis of the risk of acute kidney injury based the presence or absence of ACEi/ARB.

A VA study looking at chronic use of ACEi or ARB and the risk of acute kidney injury following cardiovascular surgery. SUNY Buffalo looked at 1,358 patients with CV surgery from 2001-2005. 50% were on ACE/ARB

  • 40% had AKI (essentialy all Modified RIFLE: Stage 1, Cr rise ≥0.3 or 50-100%)
  • 7 patients Stage 2 (Cr rise 2-3x the baseline)
  • 2 patients Stage 3 (Cr greater than 4 or >3x the baseline)
They found that use of ACEi/ARB had a 27.6% increase in risk of AKI.

Of note 18% of the patients who had AKI, their creatinine had not returned to baseline at 3 months post surgery and still qualified as AKI. This does not jive with the natural history of AKI, especialy relatively mild AKI. This makes me wonder if the baseline creatinine were abnormally low in some of the patients and the increase documented was not AKI but actually resolution of the creatine falling.

The primary concearn I have is that the study had 543 patients with AKI and only 9 had more than a doubling of creatinine. They used a very sensitive definition of AKI and like any test, when you increase the sensitivity you decrease the specificity. It is very possible that a large proportion of those patients defined as AKI didn't actually have AKI, throwing the study into doubt.

Wednesday, October 15, 2008

Some details on one of the deaths from the melamine milk contamination

This article talks about the family of the first infant to die from melamine milk contamination. The child, Yi Kaixuan was only 6 months old. He died back in May, months before any information about the contamination came out.
But on April 20, the baby wouldn't stop crying and had problems urinating. Jiao took him to the village clinic, but they couldn't pinpoint a problem.

Alarmed, Yi left his construction job and returned home. The family headed for the Gansu provincial capital, Lanzhou. On April 30, they took the baby to two city hospitals. Doctors were stunned, Yi said. They said they'd never seen a child with so many kidney stones, and the situation was critical.

A frenzy of testing followed, and the bills piled up past $145. The parents didn't sleep all night, waiting.

Around noon the next day, a doctor came to tell them their baby had died.


iPhone Medical Applications

I have four medical applications on my iPhone, of which I use two. Here is a quick review.

To show how the iPhone equipped physician approaches clinical problems I will use the DB's Medical Rants most recent acid-base problem. He presents a case with the following information:

49-year-old man, previously in good health, presents after a few weeks of progressive weakness and dizziness. He admits to polyuria. Your job is to extensively discuss his lab tests.

The first step in my mind is to fully interpret the ABG. To do this we will use the application ABG.


This simply named program is an ABG calculator that runs through the standard algorithms for detecting multiple primary acid-base abnormalities. Can't remember Winter's Formula. As long as you don't have boards coming up you can just plug'n chug and turn DB's ABG into the following:

This does two of the calculations that DB describes at length:
  1. Winter's formula (16 * 1.5 + 8 ±2) shows that the predicted pCO2 is 30-34. The patient's CO2 is 33 so the patient has isolated and appropriately compensated pCO2 of 33. ABG displays this information in the second line when it describes the acid-base disorder as "Compensated metabolic acidosis." It does not describe a second primary condition such as respiratory acidosis or alkalosis.
  2. Gap-Gap or delat-delta. The patient has a dramatically elevated anion gap at 27 (15 over the upper limit of normal of 12) but his bicarb of 16 is only 8 below normal. The difference between the delta gap and the delta anion gap is 7 (15-8) when this is added to the normal bicarbonate you get 31; so the patient had a pre-existing metabolic alkalosis with a bicarbonate of 31. ABG displays this information as the corrected bicarbonate.
The next step is adjusting his sodium for the hyperglycemia. To do this we will use Mediquations though Medical  Calc works just as well.


DB, in his discussion, states that he has unpublished data proving that no formula is effective at adjusting the serum sodium for the hyperglycemia. For those of us without his unpublished data should adjust the sodium using Katz's traditional conversion (pdf of a letter to JAMA discussing adjusting sodium for hyperglycemia in DKA. Katz's original conversion was discussed in a letter to the NEJM) of a drop in Na of 1.6 for every 100 the glucose is over 100 mg/dL. Nephrology fellows should additionally be aware of Hillier's data showing the sodium falling 2.4 for every 100 of glucose. Both Mediquations and Medical calculator adjust the sodium using Katz's conversion.

Of coarse you wouldn't know it was Katz's conversion because even if you tap on "More Info," Mediquation does not provide the reference. Likewise you will not get the reference with Medical Calc.

Though DB did not explore free water defecits in his discussion of the case this is a clinically relevent point. You can use Mediquation to calculate the water deficit.

I feel that using ABG and Mediquations will make you a more effective physician without forcing you to memorize equations used only periodically.

Tuesday, October 14, 2008

New Virus. Killing people. Scarrier than Lehman Brothers.

These emerging viral illnesses always scare the crap out of me. From the WHO:

13 October 2008 -- The results of tests conducted at the Special Pathogens Unit, National Institute for Communicable Diseases (NICD) of the National Health Laboratory Service in Johannesburg, and at the Special Pathogens and Infectious Disease Pathology branches of the Centers for Disease Control in Atlanta, USA, provide preliminary evidence that the causative agent of the disease which has resulted in the recent deaths of 3 people from Zambia and South Africa, is a virus from the Arenaviridae family.

Analysis continues at the NICD and CDC in order to characterize this virus more fully. CDC and NICD are technical partners in the Global Outbreak Alert and Response Network (GOARN).

Meanwhile, a new case has been confirmed by PCR in South Africa. A nurse who had close contact with an earlier case has become ill, and has been admitted to hospital. Contacts have been identified and are being followed-up

Love the name GOARN. Reminds me of the alien Kirk had to battle mano-a-mano.

Salt restriction in dialysis

I need to learn more about this.

Also check out The Salt Blog. Unfotunately, it looks like only one post, but a lot of comments.


Monday, October 13, 2008

Teaching Medical Students: Potassium

A couple of Fridays ago I did my second lecture for the medical students at Providence Hospital. I lectured on potassium.

The handout is good but gets a little light on content towards the end. I will revise this before the next lecture.

Potassium for Med Students

Potassium booklet form for printing
Potassium handout for iPhone

Sometimes the simplest things...

I just had a great patient encounter.

An 83 y.o. African American gentleman was referred to me for a creatinine of 1.7 mg/dL (eGFR 50 mL/min). On the initial visit he had a positive review of systems for obstruction. I added a PSA to my normal laboratory work-up of CKD and it ended up grossly positive at 42. We referred him on to urology and they diagnosed prostate Ca. He is currently getting hormone therapy.

Today he came in for his first visit with me since the cancer diagnosis. He was so appreciative. He hugged me. He acted like I saved his life. There was a strange asymmetry to the experience, I felt that I had done almost nothing more than a routine diagnosis while he was treating me like William Osler.

Sometimes the simplest things. . .

Monday, October 6, 2008

Former Felllow makes good

Rakesh Lattupalli just graduated from our fellowship in June. He was an exceptional fellow. He just finished a scientific article on the Melamine outbreak. Rakesh was the person who got me interested in the subject. The article is a nice overview of some of the scientific data on melamine toxicity.

Like me, he feels that melamine is not likely to be the entire story and a second co-factor will be identified that is critical to the development of nephrolithiasis. He suggests cyanuric acid as a possible candidate.

Melamine milk poisoning continues to make headlines

White Rabbit candies are being pulled from the shelves for failing to have less than 2.5 mg/kg melamine.

The Chinese press reported another 380 sick children in Beijing at the same time as they are declaring the milk safe. Though this seems to be a contradiction, my feeling is that stones in children will be showing up for months after the milk supply is clean as kidney stones can lie asymptomatic for months (years?) in the renal pelvis before spontaneously moving into the ureters where they cause pain, obstruction and hematuria.

The Taiwanese press provides a shockingly sophisticated article on the problems with our current toxicity knowledge of melamine and the associated debate on limits of safety. In addition to discuss limits of tolerability it goes into the differing methods of detection including high performance liquid chromatography (HPLC), liquid chromatography-tandem mass spectrometry (LC-MS/MS), gas chromatography-mass spectrometry (GC-MS). The LC-MS/MS method is apparently the most sensitive assay. One confusing aspect of the article is they swithc freely between mg/kg and ppm. One mg/kg is equal to 1 ppm.

A friend was staying with us over the week-end. She and her husband adopted a little girl from China. She was drinking chinese formula 6 months ago. She is doing well, no symptoms and when she came over she had a "kidney test." The mother asked me if she should do anything. My answer was that her daughter likely was exposed to melamine as it looks like this practice of spiking milk with melamine has been going on for awhile. I added that since her daughter was doing well and not having colicky pain, a diagnosis of nephrolithiasis would not change what you do. I recommended against doing a renal ultra-sound and wait for any symptoms which would likely never occur.

Thursday, October 2, 2008

Acid-Base lecture for ER residents

Yesterday I gave a great lecture on interpreting ABG results. I added a problems set for gap-gap analysis and added a section on the osmolar gap. I also improved the anion gap section with my new favorite nemonic. Forget PLUMSEEDS, forget MUDSLEEPS, forget MUDPILES. The new hotness is GOLD MARK:
  • M Methanol
  • A Aspirin
  • R Renal failure
  • K Ketoacidosis
This new nemonic was published in a letter in the Lancet (thanks vincent bourquin). I love that it drops the silliness of paraldehyde that no one uses anymore and drops isoniazid and iron which hardly ever cause an anion gap.

I also stumbled across a cool article on the sensitivity of the anion gap for lactic acidosis. Surprisingly an anion gap is only found in 58% of patients with an anion gap.

Additionally I cleaned up a bunch of the lecture. I still have not reformatted it for the iPhone so the handout is traditional 8.5x11 without a booklet form.
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