Hyponatraemia in AIDS

Trimethoprim-sulfamethoxazole-induced hyponatremia in an elderly lady with Achromobacter xylosoxidans pneumonia: Case report and insights into mechanism

RATIONALE

Hyponatremia occurs frequently in the hospital setting and may be attributable to a host of etiologies. Drugs are frequently implicated. Trimethoprim-sulfamethoxazole (TMP/SMX) represents a well-recognized pharmacologic precipitant of drug-induced hyponatremia, with several reports extant in the retrievable literature. Nephrologists thus debate the mechanisms giving rise to TMP/SMX-induced hyponatremia and the precise mechanism by which treatment with TMP/SMX generates reductions of serum sodium concentration remain controversial. The agent has a well-known effect of antagonizing the effects of aldosterone upon the distal nephron. Renal salt wasting and the syndrome of inappropriate antidiuretic hormone secretion represent implicated mechanistic intermediaries in TMP/SMX-induced hyponatremia.

PATIENT CONCERNS

The patient endorsed no explicit concerns.

DIAGNOSES

We describe the case of an 83-year-old female clinically diagnosed with pneumonia found to have an initial serum sodium in the range of 130 to 134 mEq/L consistent with mild hyponatremia upon admission. Sputum cultures grew Achromobacter xylosoxidans susceptible to TMP/SMX. The patient's serum sodium concentration precipitously decline following institution of treatment with TMP/SMX to 112 to 114 mEq/L during the course of 5 days.

INTERVENTIONS

Severe hyponatremia proved recalcitrant to initial therapy with supplemental salt tabs and standard doses of the vasopressin receptor antagonist tolvaptan.

OUTCOMES

Escalating doses of tolvaptan increased the patient's sodium to 120 to 124 mEq/L. The patient was transferred to another hospital for further management. During her stay, the patient did not exhibit frank or obvious clinical features consistent with hyponatremia nor readily appreciable evidence of volume depletion.

LESSONS

TMP/SMX represents a frequent, though underreported cause of hyponatremia in the hospital setting several authors believe natriuresis may represent the most common mechanism underlying TMP/SMX-induced hyponatremia. Evidence implicating natriuresis to be mechanistic in TMP/SMX-induced hyponatremia include clinically appreciable hypovolemia and resolution of hyponatremia with oral or intravenous salt repletion. Salt repletion failed to monotherapeutically enhance our patient's hyponatremiadisfavoring renal salt wasting as originately mechanistic. Contemporaneous refractoriness of serum sodium to fluid restriction nor standard doses of tolvaptan confounded our initial attempts to mechanistically attribute the patient's hyponatremia to a specific cause. Clinical euvolemia and rapid response of hyponatremia to exceptionally high doses of tolvaptan strongly favors syndrome of inappropriate antidiuretic hormone to represent the chief mechanism by which TMP/SMX exacerbates hyponatremia.

Involvement of Vasopressin in the Pathogenesis of Pulmonary Tuberculosis: A New Therapeutic Target?

Tuberculosis (TB) is a highly complex infectious disease caused by the intracellular pathogen Mycobacterium tuberculosis (Mtb). It is characterized by chronic granulomatous inflammation of the lung and systemic immune-neuroendocrine responses that have been associated with pathophysiology and disease outcome. Vasopressin (VP), a neurohypophysial hormone with immunomodulatory effects, is abnormally high in plasma of some patients with pulmonary TB, and is apparently produced ectopically. In this study, a BALB/c mouse model of progressive pulmonary TB was used to determine whether VP may play a role in TB pathophysiology. Our results show that VP gene is expressed in the lung since early infection, increasing as the infection progressed, and localized mainly in macrophages, which are key cells in mycobacterial elimination. Pharmacologic manipulation using agonist and antagonist compounds showed that high and sustained stimulation of VPR resulted in increased bacillary burdens and fibrosis at lungs, while blockade of VP receptors reduced bacterial loads. Accordingly, treatment of infected alveolar macrophages with VP in cell cultures resulted in high numbers of intracellular Mtb and impaired cytokine production. Thus, we show that VP is ectopically produced in the tuberculous lungs, with macrophages being its most possible target cell. Further, it seems that chronic vasopressinergic stimulation during active late disease causes anti-inflammatory and tissue reparative effects, which could be deleterious while its pharmacologic suppression reactivates protective immunity and contributes to shorten conventional chemotherapy, which could be a new possible form of immune-endocrine therapy.

Hyponatremia in kidney transplant patients: its pathophysiologic mechanisms

Kidney transplant patients (KTPs), and particularly those with advanced chronic kidney rejection, may be affected by opportunistic infections, metabolic alterations and vascular and oncologic diseases that promote clinical conditions that require a variety of treatments, the combinations of which may predispose them to hyponatremia. Salt and water imbalance can induce abnormalities in volemia and/or serum sodium depending on the nature of this alteration (increase or decrease), its absolute magnitude (mild or severe) and its relative magnitude (body sodium:water ratio). Hyponatremia appears when the body sodium:water ratio is reduced due to an increase in body water or a reduction in body sodium. Additionally, hyponatremia is classified as normotonic, hypertonic and hypotonic and while hypotonic hyponatremia is classified in hyponatremia with normal, high or low extracellular fluid. The main causes of hyponatremia in KTPs are hypotonic hyponatremia secondary to water and salt contraction with oral hydration (gastroenteritis, sepsis), free water retention (severe renal failure, syndrome of inappropriate antidiuretic hormone release, hypothyroidism), chronic hypokalemia (rapamycin, malnutrition), sodium loss (tubular dysfunction secondary to nephrocalcinosis, acute tubular necrosis, tubulitis/rejection, interstitial nephritis, adrenal insufficiency, aldosterone resistance, pancreatic drainage, kidney–pancreas transplant) and hyponatremia induced by medication (opioids, cyclophosphamide, psychoactive, potent diuretics and calcineurinic inhibitors). In conclusion, KTPs are predisposed to develop hyponatremia since they are exposed to immunologic, infectious, pharmacologic and oncologic disorders, the combinations of which alter their salt and water homeostatic capacity.

Water, electrolytes, and acid-base alterations in human immunodeficiency virus infected patients

The clinical spectrum of human immunodeficiency virus (HIV) infection associated disease has changed significantly over the past decade, mainly due to the wide availability and improvement of combination antiretroviral therapy regiments. Serious complications associated with profound immunodeficiency are nowadays fortunately rare in patients with adequate access to care and treatment. However, HIV infected patients, and particularly those with acquired immune deficiency syndrome, are predisposed to a host of different water, electrolyte, and acid-base disorders (sometimes with opposite characteristics), since they have a modified renal physiology (reduced free water clearance, and relatively increased fractional excretion of calcium and magnesium) and they are also exposed to infectious, inflammatory, endocrinological, oncological variables which promote clinical conditions (such as fever, tachypnea, vomiting, diarrhea, polyuria, and delirium), and may require a variety of medical interventions (antiviral medication, antibiotics, antineoplastic agents), whose combination predispose them to undermine their homeostatic capability. As many of these disturbances may remain clinically silent until reaching an advanced condition, high awareness is advisable, particularly in patients with late diagnosis, concomitant inflammatory conditions and opportunistic diseases. These disorders contribute to both morbidity and mortality in HIV infected patients.

Hyponatremia in patients with infectious diseases

Hyponatremia is a common electrolyte disturbance associated with considerable morbidity and mortality. Hyponatremia may not infrequently be present during the course of an infection, does not cause specific symptoms and may be overlooked by clinicians. Nonetheless, it may reflect the severity of the underlying process. This review focuses on the clinical and pathophysiological aspects of hyponatremia associated with infectious diseases. In the majority of cases, the fall in serum sodium concentration is of multifactorial origin owing to increased secretion of the anti-diuretic hormone either appropriately or inappropriately. Inadvertent administration of fluids may worsen hyponatremia and prolong morbidity.

Fatal cytomegalovirus-associated adrenal insufficiency in an AIDS patient receiving corticosteroid therapy

A 35-year-old homosexual man, who had already received sulfamethoxazole/trimethoprim and steroid therapy because of human immunodeficiency virus (HIV)-related Pneumocystis jiroveci pneumonia, was referred to our hospital. He was also diagnosed as having cytomegalovirus (CMV) co-infection, and started receiving intravenous gancyclovir for CMV infection on the 2nd day of admission into our hospital. He had to continue the steroid therapy because his respiratory condition did not improve. On the 10th hospitalization day, when 40 mg of prednisolone was administered, cardiopulmonary arrest suddenly occurred, and his laboratory data showed hyponatremia and hyperpotassemia. In spite of resuscitation, he died two days later. The postmortem examination revealed that he died of adrenal failure due to CMV infection. In general, CMV is thought to cause adrenalitis, but rarely leads to manifestations of adrenal insufficiency during the clinical course. It is important to be aware that grave adrenal failure due to CMV infection can develop even under steroid therapy.

Syndrome of inappropriate secretion of antidiuretic hormone and thrombocytopenia caused by cytomegalovirus infection in a young immunocompetent woman

We report the first case of the syndrome of inappropriate secretion of antidiuretic hormone (SIADH) associated with cytomegalovirus (CMV) infection. A 32-year-old woman was admitted to our hospital because of pandysautonomic signs and symptoms. Thrombocytopenia and hyponatremia were present. Serum anti-CMV IgM and IgG antibodies were positive. Despite hyponatremia, urinary osmolality exceeded plasma osmolality and plasma vasopressin levels related to plasma osmolality were high. Restriction of water intake and administration of dimethylchlorotetracycline improved hyponatremia, suggesting this patient had SIADH. In this patient, SIADH may have been caused by acute pandysautonomia that developed following CMV infection.

Hyperkalemia in patients infected with the human immunodeficiency virus: involvement of a systemic mechanism

BACKGROUND

The appearance of hyperkalemia has been described in human immunodeficiency virus (HIV)-positive patients treated with drugs with amiloride-like properties. Recent in vitro data suggest that individuals infected with HIV have alterations in transcellular K+ transport.

METHODS

With the objective of examining the presence of alterations in transmembrane K+ equilibrium in HIV-positive patients, we designed a prospective, interventional study involving 10 HIV-positive individuals and 10 healthy controls, all with normal renal function. An infusion of L-arginine (6%, intravenously, in four 30-min periods at 50, 100, 200, and 300 ml/hr) was administered, and plasma and urine electrolytes, creatinine, pH and osmolality, total and fractional sodium and potassium excretion, transtubular potassium gradient, plasma insulin, renin, aldosterone, and cortisol were measured.

RESULTS

A primary disturbance consisting of a significant rise in plasma [K+] induced by L-arginine was detected in only the HIV patients but not in the controls (P < 0.001 between groups). A K+ redistribution origin of the hyperkalemia was supported by its rapid development (within 60 min) and the lack of significant differences between HIV-positive individuals and controls in the amount of K+ excreted in the urine. The fact that the HIV-positive individuals had an inhibited aldosterone response to the increase in plasma K+ suggested a putative mechanism for the deranged K+ response.

CONCLUSIONS

These results reveal that HIV-infected individuals have a significant abnormality in systemic K+ equilibrium. This abnormality, which leads to the development of hyperkalemia after the L-arginine challenge, may be related, in part, to a failure in the aldosterone response to hyperkalemia. These results provide a new basis for understanding the pathogenesis of hyperkalemia in HIV individuals, and demonstrate that the risk of HIV-associated hyperkalemia exists even in the absence of amiloride-mimicking drugs or overt hyporeninemic hypoaldosteronism.