My hospitalized patient has developed hyperkalemia while on heparin prophylaxis. Can heparin really cause hyperkalemia and what is its mechanism?

Heparin is one of the most overlooked causes of hyperkalemia in hospitalized patients, occurring in 5-8% of treated patients, including those on thromboprophylaxis1.

The mechanism of heparin-induced hyperkalemia appears to be through suppression of aldosterone synthesis by inhibiting the function of the glomerulosa zone of the adrenal medulla2,3.  Such inhibitory action is usually of no consequence when renal function is normal and potassium excretion is not otherwise impaired.

The risk of heparin-induced hyperkalemia is increased in the elderly, those with preexisting diabetes mellitus or renal insufficiency, as well patients on concomitant use of certain drugs such as spironolactone, ACE inhibitors, NSAIDs, and trimethoprim2

Hyperkalemia is usually detected after at least 3-4 days of treatment with subcutaneous heparin, and usually resolves within a few days of  discontinuation of therapy1,2.  Fractionated heparin products such as enoxaparin may also be associated with hyperkalemia2 but the risk appears to be lower1.

Fludrocortisone has been used to normalize serum potassium in patients who  remain on heparin.4

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References

  1. Potti A, Danielson B, Badreddine R, et al. Potassium homeostasis in patients receiving prophylactic enoxaparin therapy. J Thromb Haemost 2004;2:1208-9. http://onlinelibrary.wiley.com/doi/10.1111/j.1538-7836.2004.00791.x/pdf
  2. Thomas CM, Thomas J, Smeeton F, et al. Heparin-induced hyperkalemia. Diabetes Res Clin Pract 2008;80:e7-e8. https://www.ncbi.nlm.nih.gov/pubmed/18343525
  3.  Liu AA, Bui T, Nguyen HV, et al. Subcutaneous unfractionated heparin-induced hyperkalemia in an elderly patient. Australas J Ageing 2009;28:97. https://www.ncbi.nlm.nih.gov/pubmed/19566805
  4. Brown G. Fludrocortisone for heparin-induced hyperkalemia. CJHP 2011;64:463-4. https://www.cjhp-online.ca/index.php/cjhp/article/view/1091/1394

 

My hospitalized patient has developed hyperkalemia while on heparin prophylaxis. Can heparin really cause hyperkalemia and what is its mechanism?

How should I interpret an isolated elevated hemidiaphragm on chest x-ray?

In hospitalized patients, an elevated hemidiaphragm on chest x-ray is not a rare finding and is frequently asymptomatic. It has many potential causes, including lobar collapse or surgical resection of the lung, diaphragmatic eventration, distention of stomach or colon, or phrenic nerve paralysis (1).  

Among patients with a paralyzed hemidiaphragm, damage to the phrenic nerve caused by surgery (e.g. cardiac), mediastinal tumors, cervical spine pathology, diabetes, autoimmune (e.g. vasculitis) and infectious causes (e.g. herpes zoster and polio viruses) are often cited as potential causes; most may be idiopathic, however (1,2,3).

Chest x-ray has a high negative predictive value (93%) but a poor positive predictive value for diagnosis of hemidiaphragm paralysis (1).  When in doubt, the fluoroscopic “sniff” test should be used for confirmation.  

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1. Chetta A, Rehman AK, Moxham J, et al. Chest radiography cannot predict diaphragm function. Resp Med 2005;99:39-44

2. Curtis J, Nawarawong W, Walls J, et al. Elevated hemidiaphragm after cardiac operations: incidence, prognosis, and relationship to the use of topical ice slush. Annals of Thoracic Surgery 1989;48:764-8.

3. Crausman RS, Summerhill EM, McCool FD. Idiopathic diaphragmatic paralysis: Bell’s palsy of the diaphragm? Lung 2009;187:153-157.

Contributed by Ethan Balgley, Harvard Medical Student

Disclosures: The listed questions and answers are solely the responsibility of the author and do not necessarily represent the official views of Mercy Hospital-St. Louis or its affiliate healthcare centers. Although every effort has been made to provide accurate information, the author is far from being perfect. The reader is urged to verify the content of the material with other sources as deemed appropriate and exercise clinical judgment in the interpretation and application of the information provided herein. No responsibility for an adverse outcome or guarantees for a favorable clinical result is assumed by the author. Thank you!

How should I interpret an isolated elevated hemidiaphragm on chest x-ray?

Should we routinely use broad spectrum empiric antibiotic therapy in our diabetic patients with cellulitis of the lower extremities?

The short answer is “No”!

The myth that diabetics with acute bacterial skin and skin structure infections should be routinely placed on antibiotics against gram-positives as well as gram-negatives and/or anaerobes probably originates from the extrapolation of data revolving around the frequent polymicrobial nature of diabetic foot infections.  These infections often originate from chronic ulcers and are complicated by deep tissue infection or gangrene (1), which is often not the case in our diabetic patients with cellulitis alone.  

In a recent study of the microbiology of cellulitis or cutaneous abscess in hospitalized patients, Staphylococcus and Streptococcus sp. accounted for 90% of cultured organisms in  diabetic patients, not significantly different than that of non-diabetics (1).

These finding support national guidelines which do not recommend routine use of broader spectrum antibiotics in diabetics with cellulitis or cutaneous abscess (2).  

References

1. Jenkins TC, Knepper BC, Moore SJ, et al. Comparison of the microbiology and antibiotic treatment among diabetic and nondiabetic patients hospitalized for cellulitis or cutaneous abscess. J Hosp Med 2014;9:788-794. https://www.ncbi.nlm.nih.gov/pubmed/25266293

2. Stevens DL, Bisno AL, Chambers HF, et al. Practice guidelines for the diagnosis and management of skin and soft tissue infections. Clin Infect Dis 2014;59:e10-e52. https://www.ncbi.nlm.nih.gov/pubmed/24973422

Should we routinely use broad spectrum empiric antibiotic therapy in our diabetic patients with cellulitis of the lower extremities?

When should I consider treating my hospitalized patients with asymptomatic bacteruria (ASB)?

The great majority of hospitalized patients with ASB do not need treatment with antibiotics.

In fact, there are only a couple of conditions for which treatment of ASB is indicated:  pregnant women (due to risk of pyelonephritis and low-birth infants/pre-term delivery) and before  GU instrumentation, such as transurethral resection of the prostate or other GU procedures for which mucosal bleeding is anticipated (1).  

So for the great majority of our hospitalized patients, including the elderly, diabetic women, institutionalized residents of long-term facilities, and spinal cord injury patients treatment of ASB is not indicated.  Even in the case of renal transplant patients, supportive evidence for the  use of prophylactic antibiotics in ASB is so far lacking (2).  

The estimated prevalence of ASB varies widely in the population,  with rates of 15-20% among community-dwelling women > 70 yrs of age, and 5-10% for men>65 yrs for community-dwelling men. In long-term care facility residents, 25-50% of women, 15-40% of men, and 100% of those with chronic indwelling catheters have ASB (3).  

So keep these rates in mind before attributing patient’s symptoms to ASB (ie, patient’s presentation may have nothing to do with urine findings).  It’s also worth emphasizing that pyuria accompanying ASB is not an indication for treatment.

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References

1. Nicolle LE, Bradley S, Colgan R, et al. Infectious Diseases Society of America guidelines for the diagnosis and treatment of asymptomatic bacteriuria in adults. Clin Infect Dis 2005;40:643-54.  https://academic.oup.com/cid/article/40/5/643/363229

2. Coussement J, Abramowicz D. Should we treat asymptomatic bacteriuria after renal transplantation? Nephrol Dial Transplant 2013;0:1-3. https://academic.oup.com/ndt/article/29/2/260/1913512

3. Nicolle LE. Asymptomatic bacteriuria in older adults. Geriatrics & Aging 2003;6:24-28. https://www.healthplexus.net/files/content/2003/October/0609bacteriuria.pdf

When should I consider treating my hospitalized patients with asymptomatic bacteruria (ASB)?