Consult Rounds: Low Urinary Na

Urinary Na concentration is a very useful urinary test that we use in clinical practice to decide the volume status of the patient. It is also very useful in helping decide pre renal vs intrinsic renal disease. 

There are several causes of AKI where urine Na concentration and fractional excretion of Na may be initially low, only to increase later. They are listed below

1.       Radiocontrast agent induced AKI- due to AngII increase and ischemic damage

2.       Sepsis- activation of AngII leads to initial vasoconstriction and low levels of urinary Na

3.       NSAIDs- unopposed vasoconstriction from Ang II

4.       Rhabdomyolysis- mechanism unclear

5.       Acute obstruction( initial phase)- again activation of AngII

6.       Acute GN- cytokines that lead to decrease GFR causing lowering of filtered Na load

7.       Acute rejection- similar to GN

A recent article in CJASN reviews the use of urinary studies in diagnosis of kidney diseases.

HATs off to Nephrology: The various HATs of a nephrologist

As I finished my 2 weeks on consults, I just realized why I love nephrology because it let's me wear various types of HATs

Day 1:- Consult 1: - Minimal Change Disease on kidney biopsy- starting steroids, no secondary cause. Nice GN to start the day ( putting on the GN hat)

Day 2: Consult 3: AKI on CKD in someone with CHF, getting diuresis but serum creatinine rising. Intern says, we stopped diuresis as AKI ensued.  On exam, +JVP, + B lines on our portal lung US exam, Ascites and + LE edema. Dear Intern, please don’t be nephrocentric but continue diuresis as this is renal venous congestion and bingo- 2 days later serum creatinine downtrends. Pre renal success shall we say( putting on the critical care or cardioneph hat)

Day 2: Consult 5: Na of 167, Diabetes Insipidus, bring on the ddavp please!( putting on my electrolyte hat)

Day 3: Consult 3: AKI in someone getting vanco-zosyn combination, rising vancomycin levels and creatinine going from 1mg/dl to 5mg/dl in 3 days. Kidney biopsy confirms ATN/AIN.  That vanco-zosyn combo is becoming lethal to the kidneys. How many drugs can we stop? – NSAIDS, PPIs, Vanco-zosyn. I feel like the medication police!( putting on my AKI hat)

Day 4: Consult 4: Hypomagnesemia severe enough to be admitted 3 times. PPI still on board and FeMg<2%.  Sorry but those PPIs are causing Ulcers for us the Nephrologists!( putting on my electrolyte hat)

Day 5: Consult 5: AKI in a 85 year old with MODs, septic shock and overall poor prognosis. Surprise question asked and dialysis not offered. Palliative care nephrology is important as well. Not every patient is an ideal dialysis candidate( putting on our palliative care nephrology hat)

Day7: Consult 6: Hypercalcemia and an elevated 1,25 vitamin D level- lymphoma, TB or Sarcoid and the only hypercalcemia that responds to steroids!!( putting on the onconephrology hat)

Day 8: Consult 2: AKI with someone with severe AS. Diuresis begins but guiding volume management is a tough decision. Severe AS scares me. Point of care lung US daily assessing for B lines guides management proves to be a great addition to our physical exam.( putting on the ICU nephrology hat)

Day 9: Consult 1: AKI, low platelets, low hemoglobin, rising LDH, down-trending haptoglobin and worsening HTN—bring on the TMA team. From what- virus, systemic disease, complement deficiency, not sure—but oh well onconephrology rocks! ( putting on the onconephrology hat)

Day 10: Consult 1: HTN HTN, HTN severe HTN—adrenal mass, and record high metanephrine levesl- pheochromocytoma in the house!, get the surgeons and endocrine on board( putting on the HTN specialist hat)

Day 11: Consult 2: Hyponatremia 127 but serum osmolality is 290. Hmmmm!! Paraproteins made an appearance and masquerading myeloma- more onconephrology! ( ofcourse this hat comes twice)

Day 12: Consult 3: Acute ESRD, doesn’t want HD--- but would consider acute PD –so urgent start PD done.. The new wave in PD care. Not every patient needs HD, you can in the right environment get urgent start PD and get PD arranged as outpatient- we need to make this mainstream. ( putting on the ESRD hat)

Day 12: Consult 4: AKI and proteinuria in someone with history of SLE. Kidney biopsy shows nodular sclerosis and diabetic nephropathy. No active lupus. Not all kidney biopsies in SLE are lupus nephritis.( putting on the Rheum-Renal hat)

Day 13: Consult 1: AKI, proteinuria - biopsy confirms Post infectious GN, ongoing infection treatment needed. ( putting on the GN hat)

 

Now with the above case listing- wouldn’t you feel so excited. This is why Nephrology is so much fun!! Which other field in medicine allows for so much variety!