Diagnosis of chronic kidney disease: When to refer to a nephrologist?

This is another recent review from Am Fam Physician:

Chronic kidney disease (CKD) affects 27 million adults in the U.S. It increases risk of cardiovascular disease and stroke.

Patients should be assessed annually to determine whether they are at increased risk of developing chronic kidney disease (CKD).

Risk factors for CKD include:

- diabetes mellitus
- hypertension
- older age
- cardiovascular disease
- family history of chronic kidney disease
- ethnic and racial minority status

Tests for CKD:

- Serum creatinine levels can be used to estimate the glomerular filtration rate (GFR)
- Spot urine testing can detect proteinuria

Staging of CKD is based on estimated glomerular filtration rate (GFR). Evaluation should focus on the specific type of CKD and identifying complications related to the disease stage.

When to refer to a nephrologist?

The patients with the following characteristics should be referred to a nephrologist:

- estimated glomerular filtration rates less than 30 mL per minute per 1.73 m2
- significant proteinuria
- rapid loss of kidney function

References:

Chronic Kidney Disease: Detection and Evaluation. Baumgarten M, Gehr T. Am Fam Physician. 2011 Nov 15;84(10):1138-1148.
Nephrology Cases

Acute pyelonephritis in women (2011 review)

This is a 2011 review from the official journal of the AAFP, American Family Physician:

Acute pyelonephritis is a bacterial infection of the renal pelvis and kidney most often seen in young women.

Symptoms of acute pyelonephritis

Most patients have fever, although it may be absent early in the illness. Flank pain is nearly universal.

Tests for acute pyelonephritis

A positive urinalysis confirms the diagnosis.

Urine culture should be obtained in all patients to guide antibiotic therapy if the patient does not respond to initial empiric antibiotic regimens.

Escherichia coli is the most common pathogen in acute pyelonephritis. In the past decade, there has been an increasing rate of E. coli resistance to extended-spectrum beta-lactam antibiotics.

Imaging, usually with contrast-enhanced CT is not necessary unless there is:

- no improvement in the patient's symptoms
- symptom recurrence after initial improvement

Treatment of acute pyelonephritis

Outpatient treatment is appropriate for most patients.

Oral fluoroquinolone is the initial outpatient therapy if the rate of fluoroquinolone resistance in the community is less than 10%. If the resistance rate exceeds 10%, an initial IV dose of ceftriaxone or gentamicin should be given, followed by an oral fluoroquinolone regimen.

Oral beta-lactam antibiotics and trimethoprim/sulfamethoxazole (TMP-SMX (Bactrim) are inappropriate for therapy because of high resistance rates.

References:

Diagnosis and treatment of acute pyelonephritis in women. Colgan R, Williams M, Johnson JR. Am Fam Physician. 2011 Sep 1;84(5):519-26.
Nephrology Cases

What's new in nephrology and hypertension

35% of UpToDate topics are updated every four months. The editors select a small number of the most important updates and share them via "What's new" page. I selected the brief excerpts below from What's new in nephrology and hypertension:

Glomerulonephritis

In idiopathic membranous nephropathy, among patients with protein excretion less than 8 grams/day, treatment with an ACE inhibitor or ARB increased the probability of remission.

Hypertension

There was no difference in the rate of myocardial infarction, stroke or death from cardiovascular causes between the intensive versus standard hypertension therapy groups, nor in the all-cause mortality rate. ('ACCORD BP trial'). Intensive therapy included goal systolic blood pressure less than 120 mmHg, standard therapy included goal systolic blood pressure less than 140 mmHg.

Hyponatremia

Tolvaptan is a vasopressin receptor antagonists. The long-term administration of tolvaptan appears to be safe and effective among patients with chronic hyponatremia. Responses were similar in heart failure and SIADH, and more modest in cirrhosis.

Transplantation

An increased incidence of angioedema has been noted in patients administered angiotensin-converting enzyme (ACE) inhibitors plus either sirolimus or everolimus.

Autosomal dominant polycystic kidney disease (ADPKD)

Activation of the mammalian target of rapamycin (mTOR) protein may contribute to cyst growth in autosomal dominant polycystic kidney disease (ADPKD). The inhibition of mTOR with rapamycin preserved renal function and inhibits epithelial cell proliferation and fibrosis in a mouse model of ADPKD. In a human trial, cyst volume was stable on rapamycin.

The long-acting somatostatin octreotide decreased liver volume by 5% in patients with autosomal dominant polycystic liver disease.

References:
What's new in nephrology and hypertension. UpToDate.

Twitter comments:

@kidney_boy (Joel Topf): UpToDate seems to be misrepresenting the ADPKD mTOR data. See my interpretation here: More ADPKD and sirolimus data: More definitive; less encouraging

The Lancet: Nephrology is not for normal doctors - it is for exceptionally skilled specialist physicians

From The Lancet:

Many doctors may view nephrology as a remarkable kind of intensive care. A patient presents in an acute crisis, close to death. Immediate transfer to the renal team follows, then the magical effects of dialysis, and finally recovery. Nephrology is not for normal doctors. The kidney is for exceptionally skilled specialist physicians.

Unlike fish, mammals do not seem to have renal regenerative capacity.

The silence of the kidney leads medicine to overlook its importance. This lack of awareness means that immense opportunities to prevent not only renal, but also cardiovascular, diseases are being lost.

References:
Protect the kidney, protect the heart. The Lancet.

Image source: Wikipedia, public domain.

Kidney Transplant Overview - Mayo Clinic Video

Mayo Clinic emphasizes living donor kidney transplants as the best option for patients. Martin Mai, M.D., nephrologist at Mayo Clinic offers information about living donation, statistics, including the fact that living donor kidneys last longer. Half of living donor kidneys transplanted today will still be functioning 25 years from now, whereas half of cadaveric kidneys will fail in the first 10 years.



Candy and Ellen's Story.

Oral Tolvaptan (Samsca) Is Safe and Effective Treatment for Chronic Hyponatremia

Vasopressin antagonists increase the serum sodium concentration in patients who have euvolemia and hypervolemia with hyponatremia in the short term (30 days), but their safety and efficacy with longer term administration is unknown.

In a study, 111 patients with hyponatremia received oral tolvaptan (Samsca) for 700 days.

The most common adverse effects attributed to tolvaptan were pollakiuria, thirst, fatigue, dry mouth, polydipsia, and polyuria.

Mean serum sodium increased from 130.8 mmol/L at baseline to greater than 135 mmol/L throughout the observation period.

Responses were comparable between patients with euvolemia and those with heart failure but more modest in patients with cirrhosis.

In conclusion, prolonged administration of tolvaptan maintains an increased serum sodium with an acceptable margin of safety.

Samsca (tolvaptan) Black Box Warnings

Appropriate Use

Initiate and re-initiate tx only in hospital with serum Na monitoring.

Monitor Serum Sodium

Osmotic demyelination may occur w/ rapid correction of hyponatremia (faster than 12 mEq/L/24h), resulting in dysarthria, mutism, dysphagia, lethargy, affective changes, spastic quadriparesis, seizures, coma, and death; slower rates of correction advised in pts w/ severe malnutrition, alcoholism or advanced liver disease.

Cost comparison of conivaptan (Vaprisol) versus tolvaptan (Samsca)

Conivaptan is administered IV only, the average cost per day is $573.

Tolvaptan is administered PO only, the average cost per day is $300.

References:

Oral Tolvaptan Is Safe and Effective in Chronic Hyponatremia. Journal of the American Society of Nephrology, 2010.

Samsca (tolvaptan) Black Box Warnings. Epocrates.

Cost comparison of conivaptan (Vaprisol) versus tolvaptan (Samsca) (PDF).

Lowest sodium I have ever seen http://goo.gl/QgJmf

Image source: Tolvaptan, Wikipedia, public domain.

Comments from Twitter and Facebook:

@kidney_boy: tolvaptan is safe for the patient but not their wallet at $250 per pill!

Neil Mehta: "It costs a king's ransom to keep the sodium level up! Maybe we should just say "Let them eat Salt"!"

Updated: 10/28/2010

3-gram reduction in daily salt intake would decrease coronary heart disease, stroke, and death

The U.S. diet is high in salt, with the majority coming from processed foods. Reducing dietary salt is a potentially important target for the improvement of public health.

Reducing dietary salt by 3 g per day (1200 mg of sodium per day) is projected to reduce the annual number of new cases of CHD by 60,000 to 120,000, stroke by 32,000 to 66,000, and myocardial infarction by 54,000 to 99,000 and to reduce the annual number of deaths from any cause by 44,000 to 92,000. Such an intervention would be more cost-effective than using medications to lower blood pressure in all persons with hypertension.

The cardiovascular benefits of reduced salt intake are on par with the benefits of population-wide reductions in tobacco use, obesity, and cholesterol levels.

References:

Projected Effect of Dietary Salt Reductions on Future Cardiovascular Disease. NEJM, 2010.
http://content.nejm.org/cgi/content/short/362/7/590
Sweat Bees prefer sweaty people because the human diet is so salty that their perspiration is saturated with that essential nutrient. WSJ, 2012.

Image source: Single-serving salt packets. Wikipedia, GNU Free Documentation License.

Different types of kidney transplantation - Mayo Clinic video

"Dr. Raymond Heilman, Medical Director of the Kidney Transplant Program of Mayo Clinic in Arizona, gives an overview on the different types of kidney transplantation, including living donor and paired donor exchanges, and explains what kidney donors can expect."

Water as an essential nutrient

Water has numerous roles in the human body:

- building material
- solvent
- reaction medium and reactant
- carrier for nutrients and waste products
- thermoregulation
- lubricant and shock absorber

The regulation of water balance is very precise, as a loss of 1% of body water is usually compensated within 24 hours.

Healthy adults regulate water balance with precision, but young infants and elderly people are at greater risk of dehydration.

Dehydration can affect consciousness and can induce speech incoherence, extremity weakness, hypotonia of ocular globes, orthostatic hypotension and tachycardia.

Human water requirements are not based on a minimal intake because it might lead to a water deficit due to numerous factors that modify water needs (climate, physical activity, diet and so on). On an average, a sedentary adult should drink 1.5 l of water per day, as water is the only liquid nutrient that is really essential for body hydration.



From Wikipedia:

"Water" is a song which opened the Eurovision Song Contest in 2007. The singers explained the title: "Our folklore is like water. We've chosen this title "Water", because in Bulgarian folklore there are very slow beautiful songs, which are like a lake. But we also have songs, with very fast rhythm which are like a waterfall. And my wish is this song to be like "Water", a gasp of fresh air, for the human spirit and soul. When we recorded the promo video of this song, they poured lots of rain on us, and I felt purified. I want everyone, who hears this song to feel the same way- liberated. This is a very positive song! I'm sure that people will feel it!"

References:
Water as an essential nutrient: the physiological basis of hydration. E Jéquier1 and F Constant2. European Journal of Clinical Nutrition (2010) 64, 115–123; doi:10.1038/ejcn.2009.111; published online 2 September 2009.

Presentation: Fructose drives hyperuricemia and uric acid then causes hypertension

The following presentation is by the nephrologist Joel Topf who writes the blog PBFluids.com. The subject is how fructose drives hyperuricemia and how uric acid then causes hypertension.

He used the slidecast feature on slideshare (http://www.slideshare.net/faqs/slidecast), so the slides have a full audio track.

Uric Acid, Fructose and Hypertension

View more presentations from Joel Topf.

Nephrology

Editor: V. Dimov, M.D., Assistant Professor at the University of Chicago

Nephrology Cases at ClinicalCases.org

Nephrology News at CasesBlog

Nephrology: Images in Clinical Medicine

Patient Information

Follow us and connect:





Published: 01/12/2010
Updated: 06/28/2010