Testing a new webservice: Zoho

Here is my worksheet I used to create the problems for the acid-base hand out:

Student lecture on Acid-Base

I gave a lecture to the third-year medical students at Providence hospital on Friday. I thought the lecture went well but on saturday I was going over an admit note by one of the students in the class. The patient was admitted with DKA but had a combined metabolic acidosis and respiratory alkalosis. This student didn't do the Winter's formula calculation and missed the respiratory disease. Of course so did everyone else on the admitting team.

Frustrating.

Here is the handout. I added a couple of things since giving the lecture on Friday.

Update: I corrected a mistake in one of the delta bicarb questions. Sorry.

Acid Base Handout (Student)

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Craig Langman's Editorial on the Melamine Crisis from The Journal

Craig Langman (who has made a previous appearance on PBFluids) wrote an editorial for the Melamine article and pair of letters to The Journal (one from Wang et al. from Taiwan and the other from Ho et al. from Hong Kong).

He recommends the same advice I have been giving for Americans who have adopted Chinese infants:

How should physicians in other parts of the world care for Chinese infants who may have been exposed to melamine-contaminated powdered infant formula? The American Society of Pediatric Nephrology suggests a conservative approach in asymptomatic infants,^PDF since stones presumed to have been induced by melamine ingestion appear to be passed easily after hydration, and there are currently no follow-up reports on the children studied by Guan et al. and Wang et al. Performance of abdominal ultrasonography in all potentially exposed Chinese children living in the United States would be likely to cost many millions of dollars, an expenditure difficult to justify, given that both unaffected and affected children may have no symptoms and that the meaning of a stone in an asymptomatic child is uncertain.

Langman emphasizes that each study is unable to estimate a true incidence because the populations studied were not representative of the population at risk.

He also teases the reader by mentioning that stones, which are increasing in frequency among adults, seem to be increasingly common among children. He states that this may be due to dietary and lifestyle issues but doesn't even entertain the possibility that melamine exposure here in the U.S. and around the world may be responsible. This possibility was first suggested in an insightful article in Slate. We know that melamine is found in the U.S., we don't know how long it has been here.

My personal sense is that the Slate article is just scaring people unnecessarily. if the increase in stones was do to melamine we would know it. We would know it because stones that are removed by interventions are always analyzed in a stone lab. The stones in China that were due to melamine were made of uric acid and melamine. If even a single stone in the U.S. was found to be melamine the whole medical world would go ape.

The Jounal Delivers a Bumper Crop of Melamine Articles.

The primary article is an analysis of 589 children by Na Guan

Methods

All of the children's parents were given a survey to establish demographic data and judge exposure. The investigators questioned parents on the brand and amount of formula ingested and matched it up to government data on the amount of melamine in each brand. Children were then put through varying degrees of biochemical and ultrasound testing.

All the children were under 36 months of age, the population most at risk of melamine stones.

The primary outcome was the presence of kidney stones.

The General Administration of Quality Supervision and Quarnatine of the PRC analyzed 22 brands of formula and reported the amount of melamine. The researchers then categorized each formula as:

1. High melamine (over 500 ppm)
2. Moderate melamine (less than 150 pm)
3. No-melamine.
   

Ultrasounds were reported as:

1. Definite stones
2. Suspected stones (increased sporadic, punctiform echogenicity in the kidneys or pyelocalyceal system)
   
3. No stones

Result

The all important table 1.
In 589 exams they found definite 50 stones, 112 suspected stones and 427 children were stone free.

Most of the children with stones did not oliguria, dysuria or edema. Only two of 34 stone formers (6%) had hematuria and only 1 had leukoturia (3%). None of the children with suspected stones had hematuria and only one had leukocyturia (1.3%).

Microalbuminuria was found in more of the children with stones (10%) or suspected of having stones (13.6%) compared to the stone free children (5.6%). Symptoms were not helpful in distinguishing stone formers from the stone free.

Fifty-six children had serum creatinine checked (22 with stones, 21 with suspected stones and 13 without). All of the creatinines were normal.

Interestingly 62 of 404 children had a calcium to creatinine ratio that exceeded age based targets. The 15% rate of hypercalciuria was not associated with stone risk in this study (p=0.34).

In multivariate analysis exposure to high-melamine milk (7x as likely) and pre-term birth (4.5x as likely) were significantly associated with stone formation.

The primary conclusion is that the physical and biochemical lab add nothiong to the evaluation of melamine stones. The birth history and the melamine exposure assessment are critical but need to be followed up by an ultra-sound.

The authors note that only 23 of 121 children exposed to high-melamine formula developed stones