CKD: Electrolytes and Acid/Base

• Sodium - Sometimes our kids are on sodium supplementation because their underlying kidney disease makes them polyuric and their nutrition isn’t always high sodium like the average adult diet. We are mindful of kids who have hypertension and need sodium supplementation, though rare, and ask if there are issues with free water excess

• Potassium - The big one. Typically diet controlled if possible, but occasionally require doses of Kayexalate given enterally. For our formula fed kids, we decant their formula with Kayexalate to bind it up and pour off. Then they get their formula. Remember, Kayexalate exchanges a potassium for sodium ion, so sometimes we have seen hypernatremia in some of these kids. We’ve just started using Veltassa (patiromer) in our kids, but it’s rare and for some contraindication to Kayexalate.

• Bicarb - Common with CKD progression. We try to supplement with NaBicarb 1mEq/mL to keep their levels > 20-21

• Calcium/Phos (see below)

Magnesium - Routinely runs high in PD and HD patients because they have a hard time getting rid of it with dialysis (and dialysate fluid had Mag in it). Our biggest concern comes from some GI patients who might get MagCitrate for cleanouts since Mag clearance is reduced with CKD progression. Hypomagnesemia can also happen, and can cause hypocalcemia and hypoparathyroidism (and PTH resistance). 

Kayexalate ice cream

Instructions:

1. Melt ice cream

2. Add Kayexalate dose to mixture

3. Freeze the mixture

Kayexalate candy

Notes: The candy, which has the consistency of soft fudge and a maple-flavored taste, serves as a vehicle for the medication and in addition provides 80 calories per piece. It has been tested and shown to be effective.

Ingredients:

• 1/4 lb margarine, softened

• 200 g Kayexalate powder

• 1 tsp maple extract (or other flavor)

• 3/4 cup half-and-half (cream)

• 1 lb powdered sugar, sifted

Instructions:

1. Combine margarine and Kayexalate powder until well mixed. Mixture will be crumbly.

2. Mix maple extract with half-and-half and add to Kayexalate mixture, blending until well mixed.

3. Add powdered sugar all at one time.

4. Work mixture with fingers to combine into a soft ball.

5. Divide mixture into 40 equal pieces, approximately 23 g each, either by weighing and forming balls, or making a long roll, chilling, and slicing into 40 pieces.

6. Dip in powdered sugar, if desired.

7. Wrap individually and refrigerate.

8. Each piece contains 5.0 g resin per 23 g piece of candy.

Calciphylaxis

The best treatment for this patient with calciphylaxis that has not improved with STS therapy is hyperbaric oxygen (HBO) treatment.

Managing calciphylaxis, or calcemic uremic arteriolopathy (CUA), remains challenging in patients with ESRD. The cause of CUA remains obscure and may be multifactorial, but the pathophysiology consists of calcium phosphate deposition in the walls of dermal and subcutaneous arterioles, resulting in exquisitely painful, ischemic skin necrosis. Lesions typically begin as indurated purple plaques or livedo reticularis, often in areas of subcutaneous fat and/or repetitive trauma or irritation. Some of the risk factors for CUA in patients with ESRD include warfarin, female sex, obesity, hypercoagulability, connective tissue disorders, diabetes, liver disease, and exposure to various other medications (corticosteroids, iron, calcium-containing phosphate binders, and possibly vitamin D and its analogues). Changing anticoagulation from apixaban to warfarin is contraindicated.

Management focuses mainly on risk factor management, wound care, and analgesia. Intensive dietary counseling should be given to control hyperphosphatemia in combination with non–calcium-based phosphate binders. STS is often trialed for 4‒6 weeks despite contradictory meta-analysis data for this off-label use. Ongoing wound care is essential, and surgical debridement may be necessary for control of infection but is reserved for refractory cases or those with concurrent active infection, because any surgical wound is likely to heal poorly. In this case, the findings of intact eschar do not warrant debridement.

Concurrent management of hyperparathyroidism is recommended. Vitamin D and activated vitamin D analogues are typically avoided in the setting of calciphylaxis as they can result in higher serum calcium and phosphorus concentrations or, in some cases, may trigger calciphylaxis. Surgical parathyroidectomy (or medical parathyroidectomy with cinacalcet) is often used in the setting of severe hyperparathyroidism, but the role of such therapy in a patient whose PTH level is at or below goal is not established.

Additional medical management strategies used in some cases include intensification of dialysis, bisphosphonates, vitamin K, systemic thrombolysis with a plasminogen activator, endothelin antagonists, and pentoxifylline.

Although randomized controlled trials are lacking, case reports and case series suggest that HBO can have a favorable impact on most patients with CUA who can tolerate the treatment. HBO would be a reasonable approach to managing this patient, who has nonhealing lesions despite good control of identifiable risk factors.

Udomkarnjananun S, Kongnatthasate K, Praditpornsilpa K, et al: Treatment of calciphylaxis in CKD: a systematic review and meta-analysis. Kidney Int Rep 4(2): 231‒244, 2018

An J, Devaney B, Yang Ooi K, et al: Hyperbaric oxygen in the treatment of calciphylaxis: a case series and literature review. Nephrology (Carlton) 20(7): 444‒450, 2015

McCarthy JT, El-Azhary RA, Patzelt MT, et al: Survival, risk factors, and effect of treatment in 101 patients with calciphylaxis. Mayo Clin Proc 91(10): 1384‒1394, 2016

Velasco N, MacGregor MS, Innes A, MacKay IG: Successful treatment of calciphylaxis with cinacalcet—an alternative to parathyroidectomy? Nephrol Dial Transplant 21(7): 1999‒2004, 2006

Santos PW, He J, Tuffaha A, Wetmore JB: Clinical characteristics and risk factors associated with mortality in calcific uremic arteriolopathy. Int Urol Nephrol 49(12): 2247‒2256, 2017

Don BR, Chin AI: A strategy for the treatment of calcific uremic arteriolopathy (calciphylaxis) employing a combination of therapies. Clin Nephrol 59(6): 463‒470, 2003