Markers of potassium homeostasis in salt losing tubulopathies- associations with hyperaldosteronism and hypomagnesemia

BACKGROUND

Renal loss of potassium (K+) and magnesium (Mg2+) in salt losing tubulopathies (SLT) leads to significantly reduced Quality of Life (QoL) and higher risks of cardiac arrhythmia. The normalization of K+ is currently the most widely accepted treatment target, however in even excellently designed RCTs the increase of K+ was only mild and rarely normalized. These findings question the role of K+ as the ideal marker of potassium homeostasis in SLT. Aim of this hypothesis-generating study was to define surrogate endpoints for future treatment trials in SLT in terms of their usefulness to determine QoL and important clinical outcomes.

METHODS

Within this prospective cross-sectional study including 11 patients with SLTs we assessed the biochemical, clinical and cardiological parameters and their relationship with QoL (RAND SF-36). The primary hypothesis was that QoL would be more dependent of higher aldosterone concentration, assessed by the transtubular-potassium-gradient (TTKG). Correlations were evaluated using Pearson's correlation coefficient.

RESULTS

Included patients were mainly female (82%, mean age 34 ± 12 years). Serum K+ and Mg2+ was 3.3 ± 0.6 mmol/l and 0.7 ± 0.1 mmol/l (mean ± SD). TTKG was 9.5/3.4-20.2 (median/range). While dimensions of mental health mostly correlated with serum Mg2+ (r = 0.68, p = 0.04) and K+ (r = 0.55, p = 0.08), better physical health was associated with lower aldosterone levels (r = -0.61, p = 0.06). TTKG was neither associated with aldosterone levels nor with QoL parameters. No relevant abnormalities were observed in neither 24 h-ECG nor echocardiography.

CONCLUSIONS

Hyperaldosteronism, K+ and Mg2+ were the most important parameters of QoL. TTKG was no suitable marker for hyperaldosteronism or QoL. Future confirmatory studies in SLT should assess QoL as well as aldosterone, K+ and Mg2+.

A mixed methods study of symptom perception in patients with chronic heart failure

BACKGROUND

Early heart failure (HF) symptoms are frequently unrecognized for reasons that are unclear. We explored symptom perception in patients with chronic HF.

METHODS

We enrolled 36 HF out-patients into a longitudinal sequential explanatory mixed methods study. We used objectively measured thoracic fluid accumulation and daily reports of signs and symptoms to evaluate accuracy of detected changes in fluid retention. Patterns of symptom interpretation and response were explored in telephone interviews conducted every 2 weeks for 3-months.

RESULTS

In this sample, 44% had a mismatch between objective and subjective fluid retention; younger persons were more likely to have mismatch. In interviews, two patterns were identified: those able to interpret and respond appropriately to symptoms were higher in decision-making skill and the quality of social support received.

CONCLUSION

Many HF patients were poor at interpreting and managing their symptoms. These results suggest a subgroup of patients to target for intervention.

Weight restoration in a patient with anorexia nervosa on dialysis

OBJECTIVE

We report a case of weight restoration in a patient with anorexia nervosa, end-stage renal disease (ESRD) requiring dialysis, and cardiac insufficiency.

METHOD

The technical challenges and ethical issues involved in her clinical management are reviewed. Renal insufficiency is a common complication of more severe anorexia nervosa.

RESULTS

Progression to renal failure, when it occurs, is most typically a terminal event. There are currently no published guidelines for monitoring the weight gain of patients undergoing dialysis.

CONCLUSION

We present a case of a patient who progressed from renal insufficiency to renal failure while in treatment for anorexia nervosa, and who was ultimately successfully weight restored while on renal dialysis.

Salt preference in adolescence is predicted by common prenatal and infantile mineralofluid loss

We investigated early determinants of salt preference in humans. In animals, physiological events, among them perinatal mineralofluid loss, contribute to long-term salt intake. Recent findings suggest that in humans prenatal mineralofluid loss (high levels of maternal vomiting) may increase the lifelong avidity for salt in offspring. Here we report that commonly occurring events that cause mild fluid loss and electrolyte imbalance in infancy, as well as prenatally, predict the avidity for salt in adolescents. Using questionnaires, 50 mothers recalled incidence and severity of infantile diarrhea and vomiting in their adolescent offspring. The adolescents' avidity for salt was determined by testing the preferred concentration of salt in soup, voluntary consumption of salty snack items, and by self report of salt use habits, and a dietary questionnaire. A reported history of mineralofluid loss including maternal vomiting and infantile vomiting and diarrhea increases the avidity for salt but not for sweet. Thus, commonly occurring early mineralofluid loss may contribute to lifelong salt intake. The findings raise the possibility that other causes of mineralofluid loss such as hemorrhage, exercise-induced dehydration, or neonatal diuretic therapy may also increase the avidity for salt, and its attendant health risks.

Psychogenic polydipsia after traumatic brain injury. A case report

Electrolyte abnormalities are common medical complications of traumatic brain injury (TBI). Hyponatremia is the most common of these disorders. The syndrome of inappropriate antidiuretic hormone and cerebral salt-wasting are the most well known causes of hyponatremia following TBI. In the presence of polydipsia and polyuria, psychogenic polydipsia should be included in the differential diagnosis. It is important to distinguish among these entities because treatment differs to such an extent that improper diagnosis may lead to a worsening of the patient's condition. We present a patient who presented with a new onset of polyuria and polydipsia after sustaining a TBI. Evaluation, including monitoring of fluid intake and output, serum and urine sodium and osmolarity, as well as a fluid deprivation test revealed the cause to be psychogenic polydipsia. The patient's symptoms improved after institution of a behavioral program and fluid restriction. Various models of drinking behavior have been used to identify the site of dysregulation. Dopaminergic, cholinergic, and hippocampal etiologies have been implicated in this abnormality of fluid homeostasis. If disorders of these systems can lead to psychogenic polydipsia, it is reasonable to believe that a person who has sustained a TBI would be at higher risk of developing psychogenic polydipsia.

Elderly female patients in continuing care: why are they hyperosmolar?

We have shown that the majority of elderly female patients in continuing care are in a hyperosmolar state. Thirty-two out of thirty-nine subjects had an osmolality greater than 295 mosm/kg and the mean osmolality was 302 +/- 8 mosm/kg (range 280-317 mosm/kg). No significant relationship was found with the degree of confusion (rs = 0.31; p greater than 0.05). In the second part of the study neither the measured degree of hydration, or any acute, small increases in fluid input influenced the plasma osmolality.