In the News: Hyponatremia guidelines Part 1

The NDT paper on clinical practice guidelines suggests some interesting changes in diagnosis and treatment in hyponatremia.  In the series of posts , we shall highlight the major findings of their report.

Pathophysiology update:

1.       Once the hyponatremia has been deemed hypotonic – the first test recommended is urine osmolarity and the break down after that is interesting.  If urine osm<100Mosm/kg, primary polydipsia and water intoxication is considered a likely potential.  If urine osm>100, we go into our usual categories and then order a urine Na.  If urine Na <30, low effective arterial volume is deemed and volume exam will determine next cause( from volume loss to CHF).  If urine Na>30, one either has kidney disease or diuretic use and or if ECF is reduced could be renal salt wasting or cerebral salt wasting. But if normal ECF- then SIAD.

2.       A nice table on page 21 discusses the much debated SIADH vs cerebral salt wasting.  While uric acid in the serum is same in both, it’s the BUN that is usually low in SIADH.  Urine volume is much higher in cerebral salt wasting.  And patients are usually orthostatic in the later. CVP is also low in the later.

      

    For full details click here

http://www.ncbi.nlm.nih.gov/pubmed/24569496

Kidney Treks: Physiology training for medical students

Kidney TREKS (Tutored Research and Education for Kidney Scholars) was established by the American Society of Nephrology (ASN) in 2013. 

In its second year, the program fosters interest in nephrology careers and biomedical research through a week-long research course retreat and long-term mentorship program.

This year, 25 medical students and 5 graduate students will attend an “Origins of Renal Physiology” course for students at the renowned Mount Desert Island Biologics Laboratory (MDIBL) in Bar Harbor, ME.

The course enhances first-year medical students' understanding of basic physiological concepts through hands-on experiments in a research laboratory. Organized around several modules that examine all aspects of kidney function, such as water homeostasis, salt homeostasis and secretion, acid/base homeostasis, glomerular function, and personalized medicine and genetics, the course offers opportunities for practicing classical experiments using model systems (toad, zebrafish, roundworm, shark, Xenopus oocyte) combined with modern molecular techniques.

After the course, ASN matches each student with a nephrologist-mentor who will interact with them over the course of medical school training, graduate school or postdoctoral fellowship.

Hope programs like these will enhance interest in nephrology among our medical students. 

For more information about Kidney TREKS program, please visit the ASN website. 

CLINICAL CASE 53: Answers and Summary

A 45 Y OLD CAUCASIAN MALE IS SEEN AND YOU DIAGNOSE IDIOPATHIC CALCIUM OXALATE STONE DISEASE. THE STONE FORMATION BEGINS AS SURFACES OF THE RENAL PAPILLAE START COLLECTING SUBUROTHELIAL PLAQUES CALLED RANDALL PLAQUES. WHERE DOES THIS PROCESS BEGIN?

Proximal Tubule  17%
Thin Loop of Henle 30%
Thick Loop of Henle 12%

Distal Collecting Duct 33%

Glomeruli 5%

The correct answer is Thin Loop of Henle.  

http://www.jci.org/articles/view/17038 is the article that made this point with a nice study of biopsies around the plaque sites. They performed intra operative biopsies of plaques in kidneys with calcium stone formers.  They showed this in their paper that the plaques originated in the basement membranes of thin loops of Henle and spread to the interstitum and then the urothelium.  In the patients with obesity related bypass procedures, the stones and plaques were different and instead had intratubular crystals in the collecting ducts.  

The figure 1 and figure 2 from an editorial nicely depicts it.