Approach to Patients With High Anion Gap Metabolic Acidosis: Core Curriculum 2021.

The anion gap (AG) is a mathematical construct that compares the blood sodium concentration with the sum of the chloride and bicarbonate concentrations. It is a helpful calculation that divides the metabolic acidoses into 2 categories: high AG metabolic acidosis (HAGMA) and hyperchloremic metabolic acidosis-and thereby delimits the potential etiologies of the disorder. When the [AG] is compared with changes in the bicarbonate concentration, other occult acid-base disorders can be identified. Furthermore, finding that the AG is very small or negative can suggest several occult clinical disorders or raise the possibility of electrolyte measurement artifacts. In this installment of AJKD's Core Curriculum in Nephrology, we discuss cases that represent several very common and several rare causes of HAGMA. These case scenarios highlight how the AG can provide vital clues that direct the clinician toward the correct diagnosis. We also show how to calculate and, if necessary, correct the AG for hypoalbuminemia and severe hyperglycemia. Plasma osmolality and osmolal gap calculations are described and when used together with the AG guide appropriate clinical decision making.

Utility of Hypertonic Saline and Diazepam in COVID-19-Related Hydroxychloroquine Toxicity.

BACKGROUND: Hydroxychloroquine (HCQ) poisoning is a life-threatening but treatable toxic ingestion. The scale of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection (COVID-19) and the controversial suggestion that HCQ is a treatment option have led to a significant increase in HCQ use. HCQ poisoning should be at the top-of-mind for emergency providers in cases of toxic ingestion. Treatment for HCQ poisoning includes sodium bicarbonate, epinephrine, and aggressive electrolyte repletion. We highlight the use of hypertonic saline and diazepam. CASE REPORT: We describe the case of a 37-year-old man who presented to the emergency department after the ingestion of approximately 16 g of HCQ tablets (initial serum concentration 4270 ng/mL). He was treated with an epinephrine infusion, hypertonic sodium chloride, high-dose diazepam, sodium bicarbonate, and aggressive potassium repletion. Persistent altered mental status necessitated intubation, and he was managed in the medical intensive care unit until his QRS widening and QTc prolongation resolved. After his mental status improved and it was confirmed that his ingestion was not with the intent to self-harm, he was discharged home with outpatient follow-up. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: For patients presenting with HCQ overdose and an unknown initial serum potassium level, high-dose diazepam and hypertonic sodium chloride should be started immediately for the patient with widened QRS. The choice of hypertonic sodium chloride instead of sodium bicarbonate is to avoid exacerbating underlying hypokalemia which may in turn potentiate unstable dysrhythmia. In addition, early intubation should be a priority in vomiting patients because both HCQ toxicity and high-dose diazepam cause profound sedation.

Pathophysiology and Management of Hyperammonemia in Organ Transplant Patients.

Neurologic complications are common after solid-organ transplantation, occurring in one-third of patients. Immunosuppression-related neurotoxicity (involving calcineurin inhibitors and corticosteroids), opportunistic central nervous system infections, seizures, and delirium are some of the causes of neurologic symptoms following solid-organ transplantation. An uncommon often missed complication posttransplantation involves buildup of ammonia levels that can lead to rapid clinical deterioration even when treated. Ammonia levels are not routinely checked due to the myriad of other explanations for encephalopathy in a transplant recipient. A treatment of choice for severe hyperammonemia involves renal replacement therapy (RRT), but there are no guidelines on the mode or parameters of RRT for reducing ammonia levels. Hyperammonemia in a transplant recipient poses specific challenges beyond the actual condition because the treatment (RRT) involves significant hemodynamic fluctuations that may affect the graft. In this review, we describe a patient with posttransplantation hyperammonemia and discuss the pathways of ammonia metabolism, potential factors underlying the development of hyperammonemia posttransplantation, and choice of appropriate therapeutic options in these patients.

Uremic Pericarditis: Distinguishing Features in a Now-Uncommon Clinical Syndrome.

We present the case of a 47-year-old man with a history of diabetes mellitus and diabetic nephropathy who was admitted to our hospital with acute uremic myopericarditis. Echocardiography demonstrated a fibrinous pericardial effusion. The patient was initiated on hemodialysis for hyperkalemia, metabolic acidosis, and uremia. He subsequently developed shock from cardiac tamponade, which required emergent pericardiocentesis. He was notably without tachycardia while he was hypotensive, and his admission electrocardiogram did not show typical ST- or PR-segment changes typically associated with acute pericarditis. This case highlights important differences between uremic pericarditis and other prevalent types of acute pericarditis, including the lack of tachycardia during tamponade and normal electrocardiography. Uremic pericarditis is now a less common diagnosis. It is often seen in the setting of previously undiagnosed advanced kidney disease or when patients are ineffectively dialyzed. Given its atypical features, low incidence, and adverse attendant complications, internists must maintain a high degree of suspicion to correctly diagnose acute uremic pericarditis.

Dialysis in the undocumented: The past, the present, and what lies ahead.

In many states undocumented immigrants with end stage renal disease (ESRD) do not have access to regular, thrice weekly dialysis. The term "compassionate dialysis" is used to describe dialysis that is provided on an emergent basis, when patients are in extremis from symptoms of volume overload or suffer from life-threatening electrolyte abnormalities. In this editorial, one particularly poignant anecdote is presented from the experience of one of the authors (AZF) as a nephrologist in Texas, a state where undocumented immigrants have faced difficulties in accessing regular dialysis. We then describe the legislation that allows the right to regular dialysis to be determined on a state by state basis. We offer some potential solutions to this challenging issue, and we describe the difficulties that lay ahead given the uncertain future of the Affordable Care Act.

Recent Developments in the Classification, Evaluation, Pathophysiology, and Management of Scleroderma Renal Crisis.

Scleroderma renal crisis (SRC) is an uncommon complication of systemic sclerosis. Despite the advent of angiotensin-converting inhibitor therapy, SRC remains a life-threatening complication. Recent studies have contributed to a better understanding of SRC, but much remains unknown regarding its pathophysiology, risk factors, and optimal management. Genetic studies provide evidence that immune dysregulation might be a contributing factor, providing hope that further research in this direction might illuminate pathogenesis and provide novel predictors for this complication.

The spectrum of nephrocutaneous diseases and associations: Genetic causes of nephrocutaneous disease.

There are a significant number of diseases and treatment considerations of considerable importance relating to the skin and renal systems. This emphasizes the need for dermatologists in practice or in clinical training to be aware of these associations. Part I of this 2-part continuing medical education article reviews the genetic syndromes with both renal and cutaneous involvement that are most important for the dermatologist to be able to identify, manage, and appropriately refer to nephrology colleagues. Part II reviews the inflammatory syndromes with relevant renal manifestations and therapeutic agents commonly used by dermatologists that have drug-induced effects on or require close consideration of renal function. In addition, we will likewise review therapeutic agents commonly used by nephrologists that have drug-induced effects on the skin that dermatologists are likely to encounter in clinical practice. In both parts of this continuing medical education article, we discuss diagnosis, management, and appropriate referral to our nephrology colleagues in the context of each nephrocutaneous association. There are a significant number of dermatoses associated with renal abnormalities and disease, emphasizing the need for dermatologists to be keenly aware of their presence in order to avoid overlooking important skin conditions with potentially devastating renal complications. This review discusses important nephrocutaneous disease associations with recommendations for the appropriate urgency of referral to nephrology colleagues for diagnosis, surveillance, and early management of potential renal sequelae.

The spectrum of nephrocutaneous diseases and associations: Inflammatory and medication-related nephrocutaneous associations.

There are a significant number of dermatoses associated with renal abnormalities and disease, and dermatologists need to be keenly aware of their presence in order to avoid overlooking important skin conditions with potentially devastating renal complications. This review discusses important nephrocutaneous disease associations and recommendations for the appropriate urgency of referral to nephrology colleagues for diagnosis, surveillance, and early management of potential renal sequelae. Part II of this 2-part continuing medical education article addresses inflammatory and medication-related nephrocutaneous associations.

Assessment and management of hypertension in transplant patients.

Hypertension in renal transplant recipients is common and ranges from 50% to 80% in adult recipients and from 47% to 82% in pediatric recipients. Cardiovascular morbidity and mortality and shortened allograft survival are important consequences of inadequate control of hypertension. In this review, we examine the epidemiology, pathophysiology, and management considerations of post-transplant hypertension. Donor and recipient factors, acute and chronic allograft injury, and immunosuppressive medications may each explain some of the pathophysiology of post-transplant hypertension. As observed in other patient cohorts, renal artery stenosis and adrenal causes of hypertension may be important contributing factors. Notably, BP treatment goals for renal transplant recipients remain an enigma because there are no adequate randomized controlled trials to support a benefit from targeting lower BP levels on graft and patient survival. The potential for drug-drug interactions and altered pharmacokinetics and pharmacodynamics of the different antihypertensive medications need to be carefully considered. To date, no specific antihypertensive medications have been shown to be more effective than others at improving either patient or graft survival. Identifying the underlying pathophysiology and subsequent individualization of treatment goals are important for improving long-term patient and graft outcomes in these patients.

Use of Urea for the Syndrome of Inappropriate Secretion of Antidiuretic Hormone: A Systematic Review.

Importance: Hyponatremia and the syndrome of inappropriate secretion of antidiuretic hormone (SIADH) are associated with significant mortality and morbidity. The effectiveness and safety of oral urea for SIADH are still debated. Objective: To evaluate the efficacy and safety of urea for the treatment of SIADH. Evidence Review: A systematic search of Medline and Embase was conducted for controlled and uncontrolled studies of urea for SIADH in adult patients. The primary outcome was serum sodium concentration after treatment. Secondary outcomes included the proportion of patients with osmotic demyelination syndrome (ODS), intracranial pressure, and resource use such as length of stay. Findings: Twenty-three studies involving 537 patients with SIADH were included, of which 462 were treated with urea. The pooled mean baseline serum sodium was 125.0 mmol/L (95% CI, 122.6-127.5 mmol/L). The median treatment duration with oral urea was 5 days. Urea increased serum sodium concentration by a mean of 9.6 mmol/L (95% CI, 7.5-11.7 mmol/L). The mean increase in serum sodium after 24 hours was 4.9 mmol/L (95% CI, 0.5-9.3 mmol/L). Adverse events were few, mainly consisting of distaste or dysgeusia, and no case of ODS was reported. Resource use was too infrequently reported to be synthesized. Conclusions and Relevance: In this systematic review of the use of urea in SIADH and despite the lack of randomized clinical trials, lower-quality evidence was identified that suggests that urea may be an effective, safe, and inexpensive treatment modality that warrants further exploration.