Disturbances Of Water Metabolism Research Articles

#2241 Validation of a new formula for total body water in peritoneal dialysis patients

Abstract Background and Aims Peritoneal dialysis (PD) adequacy, assessed primarily by Kt/V, is crucial in routine clinical practice for detecting issues with PD treatment. This metric relies on urea levels and its volume (V) distribution, classically equivalent to total body water (TBW). TBW estimation, commonly achieved through the Watson and Watson (WW) formula, lacks dialysis patients in its original study, it also excluded patients with water metabolism disturbances, raising concerns about its generalizability to this population. Responding to this need, a new formula (NF) for calculating TBW in PD patients was developed in our center, with the aim of improving the correlation between administered Kt/V and clinical outcomes. Consequently, this study seeks to validate the proposed formula by applying it to a population. Method A prospective study conducted at a single center within PD program involved the collection of data on adequacy and Body Composition Monitoring (BCM) spanning from May 2023 to January 2024. TBW was calculated using the WW formula and the proposed new formula (TBW BI=0.36*Height+0.241*weight−9.675*BSA−26.234 for man and TBW BI=0.36*Height+0.241*weight−9.675*BSA−28.926 for woman). Categorical variables are presented as frequencies and percentages, continuous variables as means and standard deviations, or medians and interquartile ranges for variables with skewed distributions. A p-value < 0.05 was considered significant. Both formulas were subjected to correlation analysis with BCM TBW to assess mean differences using a paired-samples T test. Additionally, the resulting Kt/V values were compared, along with an examination of concordance in the detection of Kt/V values below 1.7. Results 66 measurements were collected from 36 PD patients. 29.2% (n = 10) were female, and the mean age was 59.7 years. Both formulas exhibited strong correlations with BCM TBW (WW: ρ = 0.949 and NF: ρ = 0.953, p < 0.001). BCM TBW showed a significant difference from WW TBW (34.8 vs. 38.1 liters, p < 0.001), but not when compared to the new formula (34.8 vs. 33.9, p = 0.06). The resulting BCM-derived Kt/V significantly differed from both formulas, with a larger mean difference compared to the WW formula (BCM: 2.71 vs. WW: 2.42, p < 0.001, and vs. the new formula: 2.77, p = 0.04). There was a perfect association between the use of NF and identification of BCM derived KtV measurements under the 1.7 target (Phi = 1, p < 0.001), an association that was strong for WW (Phi = 0.69, p < 0.001). Conclusion Errors in quantifying PD adequacy can lead to delayed detection of technical issues or inappropriate adjustments to already adequate prescriptions. We present a novel formula, specific for the PD population, reducing errors in PD quantification, particularly in settings where BCM is not available.

#2234 A new formula for total body water in peritoneal dialysis patients

Abstract Background and Aims Peritoneal dialysis (PD) adequacy, assessed primarily by Kt/V, is crucial in routine clinical practice for detecting issues with PD treatment. This metric relies on urea levels and its volume (V) distribution, classically equivalent to total body water (TBW). TBW estimation, commonly achieved through the Watson and Watson (WW) formula, lacks dialysis patients in its original study, it also excluded patients with water metabolism disturbances, raising concerns about its generalizability to this population. Despite limitations, WW has been widely used in trials assessing optimal dialysis dosage in the PD population. Body composition monitoring (BCM) with bioimpedance (BI) offers a more reliable method for TBW determination, commonly used in dialysis programs for quantifying overhydration. However, its higher cost and limited availability compared to estimate formulas pose challenges. Thereby, this study aims to compare TBW values derived from the WW formula and BCM analysis with BI. Additionally, intends to create a new, patient-specific TBW formula based on biometric measurements for PD. Method We retrospectively analyzed adequacy measurements and BCM data from a Portuguese PD center. Patient information included age, sex, height, weight, and BCM-TBW and Percentage Body Fat (PBF). Derived parameters encompassed WW-derived TBW, Body Surface Area (BSA) via the DuBois formula and Body Mass Index (BMI). Statistical analysis, using Microsoft Excel 2017 and IBM SPSS version 25, with a p-value<0.05 considered significant, followed by a step-wise approach: Results 400 measurements were collected from 90 chronic PD patients. 25.1% (n = 23) were female (101 measurements), with a mean age of 56.2 ± 11.9 years. Mean weight was 74.0 ± 12.5 kg, BMI 26.4 ± 4.1 and BSA 1.80 ± 0.80. BCM TBW obtained was significantly lower compared to WW-TBW (33.7 and 38.4 litters respectively, mean difference −4.65 ± 4.17, P < .001). This difference correlated positively with increased PBF (ρ = 0.73, P < .001). BCM TBW correlated positively with weight, height, BMI and BSA (ρ = 0.62, ρ = 0.68, ρ = 0.28 and ρ = 0.62, respectively, with P < .001 overall), without correlation with age (ρ = 0.0, P = .99). For linear regression analysis, the first step was to exclude outlier values for BCM TBW using median ± 1.5 x interquartile range resulting in 383 measurements comprised between 22.15 and 44.95 L. A multiple linear regression using BSA, height, weight and sex to predict BCM TBW. The overall regression model was statistically significant (R2 = 0.59, F (4 378) = 138.17, P < .001). All the variables significantly contributed to the model at predicting BCM TBW (BSA: β = −0.283, P < .001; Height: β = 0.495, P < .001; Weight: β = 0.56, P < .001; Sex: β = 0.237, P < .001). Two formulas were extrapolated from this regression: Conclusion We present a pivotal formula for TBW calculation in PD patients, aiming to improve the correlation between provided Kt/V and clinical outcomes. This addresses the exclusion of diverse patient characteristics in previous studies. However, given the new evidence challenging the association between Kt/V and clinical outcomes in PD, it becomes imperative to appropriate measures for PD adequacy and subject them to examination in novel randomized clinical trials.

Diabetes insípida

Diabetes insipidus: Diabetes insipidus is an uncommon disturbance in water metabolism resulting from a deficiency in the action of the antidiuretic hormone caused either by neurohypophyseal disorder difficulty its secretion (central diabetes insipidus) or by impaired renal response (nephrogenic diabetes insipidus). Clinically is characterized by polydipsia and polyuria. Water deprivation test, which assesses the ability of the kidney to concentrate urine, is the confirmatory diagnostic test. Differential diagnosis includes: primary polydipsia (hypotonic urination secondary to excessive fluid intake) and osmotic diuresis. In order to distinguish between central and nephrogenic diabetes insipidus, vasopressin levels and desmopressin response have to be assessed. Desmopressin is the treatment of central diabetes insipidus. On the other hand, and in order to facilitate kidney urine concentration, diuretic drugs (mainly thiazide diuretics) appear as the treatment of nephrogenic diabetes insipidus.

Causes, diagnosis and differential diagnosis of hyponatremia

Hyponatremia is a common electrolyte disorder that arises from disturbances in water metabolism. In cases of acute advanced hyponatremia, serious symptoms are predominant, while chronic mild hyponatremia causes minor symptoms such as slowness, depression or unsteadiness of gait. Any therapy of hyponatremia depends on the severity of its symptoms and on its specific etiology and diagnosis. Concerning the differential diagnosis of the type of hyponatremia, it is initially helpful to distinguish between euvolemic, hypervolemic and hypovolemic forms of hyponatremia. In order to distinguish between these 3 types of hyponatremia, it is best to assess the spontaneous urinary sodium concentration and to consider evidence from the medical history and the physical examination. Once the type of hyponatremia has been diagnosed, the next step is to decide which of the known etiologies of hyponatremia applies. Diagnostic problems may arise in mixed hyponatremia, a condition in which different types and etiologies of hyponatremia occur at the same time. In such cases it may be best to determine what appears to be the leading diagnosis. Another kind of diagnostic difficulty often occurs in simultaneous diuretic use. It may help to distinguish to which extracellular volume the types of hyponatremia relate on the basis of the fractional excretion of uric acid rather than on the urinary sodium concentration.

Discussion on the phlegm diseases theory in traditional Chinese medicine

The article points that phlegm diseases should not only be summarized into pathological products resulting from disturbance of water metabolism in the body,but be expressed as pathological products resulting from the essence of the water and food can not become Qi,blood and body fluids.The concept on the difference of visible phlegm and invisible phlegm is wrong.Phlegm is pathological links of diseases,should not be classified as a secondary pathogen.In the textbook of Basic Theory of Traditional Chinese Medicine,phlegm and fluid retention should be discussed separately; their concepts,pathogens and pathogenic characteristics should not be discussed together.But we think the discussion of visible phlegm and invisible phlegm should be substituted as discussion of the difference between phlegm and phlegm diseases. Key words: Phlegm; Body fluids; Secondary pathogen

Acid base and fluid electrolyte disturbances in Chronic Kidney Disease

Abstract The kidneys maintain homeostasis in the body avoiding significant alterations in the balance of fluid electrolyte or acid–base balance until the Glomerular filtration rates (GFR) declines to below 25 ml/min due to a series of adaptive changes, both Renal and extra renal. With progressive decline in renal function these mechanisms are overwhelmed resulting in disturbances in water metabolism contributing to hyponatremia and hypernatremia. The altered regulation of sodium transport causes disturbed volume status including volume overload and depletion. The incidence of Hyperkelemia and metabolic acidosis is more frequent in Chronic Kidney Disease (CKD) with GFR below 10 ml/min. In this review article we will attempt to review the renal and extra renal adaptation mechanisms maintaining fluid, electrolyte and acid base balance in CKD along with factors which cause failure of these mechanisms. The article will also highlight the common fluid electrolyte and acid base disorders in CKD and their treatment.

Kidney function in mice lacking aldosterone

To explore the effects of decreased amounts or absence of aldosterone, we have disrupted the gene coding for aldosterone synthase (AS) in mice and investigated blood pressure and kidney function in AS+/+, AS+/-, and AS-/- mice. AS+/- mice have normal blood pressures and show no abnormalities in electrolytes or kidney gene expression, but they have significantly higher than normal urine volume and lower urine osmolality. In contrast, the AS-/- mice have low blood pressure, abnormal electrolyte homeostasis (increased plasma concentrations of K+, Ca2+, and Mg2+ and decreased concentrations of HCO3(-) and Cl- but no difference in the plasma Na+ level), and disturbances in water metabolism (higher urine output, decreased urine osmolality, and impaired urine concentrating and diluting ability). Absence of aldosterone in the AS-/- mice induced several compensatory changes: an increased food intake-to-body weight ratio, an elevated plasma concentration of glucocorticoids, and strong activation of the renin-angiotensin system. Parallel with the markedly increased synthesis and release of renin, the AS-/- mice showed increased expression of cyclooxygenase-2 (COX-2) in macula densa. On salt supplementation, plasma electrolyte concentrations and kidney renin and COX-2 levels became similar to those of wild-type mice, but the lower blood pressure of the AS-/- mice was not corrected. Thus absence of aldosterone in AS-/- mice results in impairment of Na+ reabsorption in the distal nephron, decreased blood pressure, and strong renin-angiotensin system activation. Our data show the substantial correction of these abnormalities, except the low blood pressure, by high dietary salt does not depend on aldosterone.

Endocrinological outcome following first time transsphenoidal surgery for GH-, ACTH-, and PRL-secreting pituitary adenomas.

To study remission rates and pituitary functions following transsphenoidal surgery of newly diagnosed GH-, ACTH-, and PRL-secreting pituitary adenomas. Out of a series of 329 newly diagnosed pituitary adenomas, 131 (39.8%) were hormone (67 GH-, 27 ACTH-, 37 PRL-) secreting. PRL-secreting adenomas were subjected to surgery because they failed to respond to previous medical treatment therapy. The data on secreting adenomas, regarding the results of standardised endocrinological testing, MRI findings and water metabolism disturbances, were extracted retrospectively from the pituitary data-base of the hospital. The mean follow-up was 3.7 years. The overall remission rate for PRL-secreting adenomas (27%) was significantly lower than for GH- (71.6%) and ACTH-secreting (81.5%) ones. Remission rates correlated negatively with the magnitude of preoperative hormone excess (not in Cushing's disease), tumour size (not in prolactinoma) and invasiveness. Generally, the improvement of the adenopituitary functions was statistically significant during the first three postoperative months, and thereafter remained unchanged. Diabetes insipidus persisting for more than three months occurred with similar frequency in the three patient groups (in 9.4% of GH-, in 6.7% of ACTH-, and in 10% of PRL-secreting adenomas). Tumour regrowth occurred more often in PRL-(20%) than in ACTH- (9.1%) and GH- (0%) secreting tumours. In GH- and ACTH-secreting pituitary adenomas, remission rates were significantly higher and recurrence rates lower than in PRL-secreting adenomas, which had failed to respond to previous medical therapy. The overall postoperative adenopituitary function was improved in all patient groups. Diabetes insipidus occurred with similar frequency in all patient groups. When reporting on results of surgery for secreting pituitary adenomas, not only remission and recurrence rates, but also the results of the pituitary function should be included.

Water metabolism disturbances at different stages of primary thyroid failure.

The aim of the present study was to study salt and water metabolism in thyroid deficiency. We performed an oral water loading test (OWL) and a hypertonic 5% saline infusion test (HSI) in 16 patients with overt primary hypothyroidism before replacement treatment (PRE group) and after, in eight patients with subclinical hypothyroidism (SUB group) and in 16 normal individuals (CG group). In the PRE group, a lower free water clearance was detected in the OWL (P < 0.022), with lower plasma osmolality (OWL: P < 0.005; HSI: P < 0.001) and arginine vasopressin (AVP) (OWL: P < 0.001; HSI: P < 0.001) than the CG group, across both tests; they normalized with the replacement treatment. The same plasma abnormalities were detected in the SUB group with the HSI. Although the AVP and thirst thresholds did not differ between the groups, the lag between them was lower in the PRE (4.1+/-3.2 mOsm/kg) and SUB group (2.6+/-2.1 mOsm/kg) than in the CG group (13.3+/-9.2 mOsm/kg) (P < 0.05). There were no differences in atrial natriuretic hormone (ANH), plasma renin activity (PRA) and plasma aldosterone among the groups. These results indicate that plasma hypo-osmolality and low levels of AVP are present in primary hypothyroidism, and indeed are already present in the subclinical phase of the disease. An overlap between the thresholds of thirst and AVP seem to play a role in these abnormalities, but ANH, PRA and plasma aldosterone do not appear to contribute.

Abnormalities of Water Metabolism after Surgery for Optic/Chiasmatic Astrocytomas in Children

A major concern during the early postoperative period after surgical resection of optic chiasmatic gliomas is the derangement of sodium and water metabolism which may add to the morbidity of the procedure. The purpose of this study was to characterize the abnormalities of water and sodium metabolism in children with optic chiasmatic gliomas treated surgically at British Columbia’s Children’s Hospital and to identify therapeutic modalities which might prevent or ameliorate the development of these complications. A retrospective chart review of children with optic/chiasmatic gliomas undergoing operations on the tumor was performed and the pre- and postoperative radiographs reviewed by an independent neuroradiologist. There were 11 patients who underwent 13 operations for either resection (n = 9) or biopsy (n = 4) of their optic chiasm tumor. The extent of resection in patients undergoing more than simple biopsy ranged from 83 to 99%, and all patients with resection had exophytic tumor extending into the hypothalamus. Postoperative syndrome of inappropriate antidiuretic hormone secretion (SIADH) and/or diabetes insipidus occurred after 8 of the 9 tumor resections and was associated with significant morbidity. No disturbance of water metabolism occurred after biopsy only. In patients with SIADH, the urinary sodium level rose markedly 6–12 h prior to the development of hyponatremia, and it was concluded that this was a valuable predictor of impending hyponatremia. Replacement of urine output was noted to be the most reliable way to avoid rapid fluctuations in serum sodium and to avoid the morbidity of diabetes insipidus or SIADH and is recommended in the postsurgical patients who cannot regulate fluid intake.

Language guiding therapy: the case of dehydration versus volume depletion.

Indiscriminate use of the terms dehydration and volume depletion, so carefully crafted by our predecessors, risks confusion and therapeutic errors. These two conditions should be distinguished at the bedside and in how we speak to one another. Dehydration largely refers to intracellular water deficits stemming from hypertonicity and a disturbance in water metabolism. The diagnosis of dehydration cannot be established without laboratory analysis of p[Na +] or calculation of serum tonicity. In contrast, volume depletion describes the net loss of total body sodium and a reduction in intravascular volume and is best termed extracellular fluid volume depletion. The diagnosis of this condition relies principally on history, careful physical examination, and adjunctive data from laboratory studies. The pathophysiology of both dehydration and extracellular fluid volume depletion must be understood if these conditions are to be recognized and appropriately treated when they occur separately or together. There is no inclusive therapy for all situations. For example, indiscriminate treatment with 0.45% saline cannot be recommended when these conditions coexist because extracellular fluid volume depletion is often treated rapidly with 0.9% saline and dehydration is often treated more slowly with 5% dextrose.

Changes of the total water content and magnetic relaxation characteristics of the liver and small intestine in vagotomy

Bilateral subdiaphragmatic truncal vagotomy in rats results in a disturbance of water metabolism in the liver and small intestine which manifests itself in an increase of the total water content, prolongation of the spin-lattice and spin-spin relaxation, and in a distortion of the correlation between them. The dynamics of water metabolism is of a onepeak nature in the liver with a maximum after 7 days, whereas in the small intestine it is of a dual-peak type with peaks at 7 and 30 days. Near-normalization of the water balance in the digestive organs occurs 220 days later.

The Literature of Medicine: Reviews and Notes: Clinical Disturbances of Water Metabolism; and Clinical Disorders of Fluid and Electrolyte Metabolism

The Literature of Medicine: Reviews and Notes: Clinical Disturbances of Water Metabolism; and Clinical Disorders of Fluid and Electrolyte Metabolism

Reviews and Notes: Clinical Disturbances of Water Metabolism; and Clinical Disorders of Fluid and Electrolyte Metabolism

Reviews and Notes: Clinical Disturbances of Water Metabolism; and Clinical Disorders of Fluid and Electrolyte Metabolism

Book Review: Clinical disturbances of water metabolism

Book Review: Clinical disturbances of water metabolism

Effects of chronic alcohol consumption and of dehydration on the supraoptic nucleus of adult male and female rats

Ethanol ingestion affects the hypothalamo-neurohypophysial system resulting in increased diuresis, dehydration and hyperosmolality. We studied the supraoptic nucleus, of the hypothalamus, in ethanol-treated rats, to determine if ethanol alone and/or the associated disturbances of water metabolism lead to structural alterations in a nucleus known to play a central role in fluid homeostasis. Groups of male and female rats were ethanol-treated until 12 and 18 months of age and compared with age-matched pair-fed controls. Twelve and 18-month-old control groups and 12-month-old water control groups (rats submitted to chronic dehydration) were also included in this study in an attempt to differentiate between the effects of undernutrition and dehydration/hyperosmolality, and the specific neurotoxic effects of ethanol. We estimated the volume of the supraoptic nucleus and the numerical density of its neurons and calculated the total number of supraoptic neurons. The volume of both supraoptic neurons and neuropil were also estimated. In immunostained material the ratio of vasopressin to oxytocin neurons and the cross-sectional areas of the two neuronal types were evaluated. There was marked neuronal loss in alcohol-treated rats, but the volume of the supraoptic nucleus was increased. The increase in the volume of the supraoptic nucleus correlated with and was due to increases in the volume of its remaining neuronal cell bodies and in the volume of its neuropil. The increase in cell body volume was particularly marked for vasopressin neurons. No significant differences were found between controls and pair-fed controls in any of the parameters investigated. In water control rats, the volume of the supraoptic nucleus and of the supraoptic neurons and neuropil was also greater than in pair-fed controls. However, the variations found were not as marked as in ethanol-treated rats and there was no cell loss. These findings reveal, for the first time, that chronic ethanol consumption affects the morphology of supraoptic neurons and neuropil and, consequently, the structure of the entire supraoptic nucleus. Moreover, this study supports the view that ethanol has direct neurotoxic effects on supraoptic neurons because the alterations that occur are not mimicked in animals in which water metabolism alone is disturbed.

Water Metabolism and Postconcussional Symptoms 5 Weeks after Mild Head Injury

Posttraumatic diabetes insipidus has been reported as a sequela to head injury. It is unknown whether subclinical types of diabetes insipidus, or other types of water metabolism disorders, occur after mild head injury (MHI) and, if so, whether they are related to the persistence of postconcussional symptoms. MHI patients (n = 38) were screened for disturbances of water metabolism by comparing plasma and urine osmolalities at about 5 weeks after the trauma. Eight patients had evidence of an increased plasma osmolality together with a relatively decreased urine osmolality after an overnight fast. The presence of this disturbance was significantly related to the persistence of postconcussional symptoms. The results suggest that subclinical disturbances of water metabolism may, among other factors, be related to the persistence of symptoms after MHI.

Role of diuretics, hormonal derangements, and clinical setting of hyponatremia in medical patients.

Because hyponatremia is frequently associated with preceding diuretic treatment and unrestricted fluid intake--conditions which have not been addressed sufficiently in published literature--we studied the pathophysiology and the clinical setting of such hyponatremia in a large group of internal medicine patients. We observed: a) Of an initial 310 patients with chemical hyponatremia only 204 (64%) had an associated plasma hypoosmolality. Since a normal plasma osmolality excludes a disturbance of water metabolism only the 204 patients with hypoosmolar hyponatremia were included in the study. This data shows that plasma osmolality is an essential measurement in any evaluation of hyponatremia. b) In 204 consecutive patients with hypoosmolar hyponatremia the electrolyte disturbance was related to advanced congestive cardiac failure in 25%, decompensated liver cirrhosis in 18%, volume contraction in 28%, syndrome of inappropriate antidiuretic hormone secretion in 19% and renal insufficiency in 4%. c) Plasma vasopressin was measurable in 90% of the 204 patients. It is known that radioimmunoassays to measure vasopressin fail to reliably detect low concentrations of circulating vasopressin (less than 0.5 pg/ml). It may therefore be stated that hypoosmolar hyponatremia was generally characterized by a failure of antidiuretic hormone suppression. d) Mean daily fluid intake of hyponatremic patients was 2.35 +/- 0.15 l. In the presence of stimulated vasopressin this large a fluid intake is bound to worsen the severity of hyponatremia. e) Of 204 patients 126 were treated with diuretics at the time of study. In these patients hyponatremia worsened during such treatments and was associated with evidence of prerenal azotemia. However there were no significant differences between diuretic-treated and -untreated patients with respect to plasma vasopressin stimulation and amount of fluid intake.(ABSTRACT TRUNCATED AT 250 WORDS)

Membrane defect affecting water permeability in human epilepsy.

McQUARRIE wrote that a disturbance in water balance perhaps affecting the central nervous system more specifically seems to be closely identified with the aetiology of epilepsy1. McQuarrie and Teglbjaerg2 studied water balance in relation to seizure frequency, establishing the ictogenic effect of excessive water ingestion, and the therapeutic value of dehydration. Schneider3 has reported that exacerbation of petit mal in children and adults is associated with reduction in urinary volume, and that clinical remission coincidences with an increase in water excretion. Reynolds4 has demonstrated disturbances in the whole body distribution of water in epilepsy, with a magnitude proportional to the frequency of attacks, concluding that the changes in body water and sodium are linked in some way to the aetiology of the disease. Wender and Strzyzewski5 have shown that water loading in epileptics produces seizures only in cases where there is also a marked increase in the water content of erythrocytes. There is thus abundant evidence linking epilepsy with water metabolism. Furthermore, diuretics, such as acetazolamid, are used in the therapy of epilepsies6. But the mechanism of the disturbance of water metabolism at the subcellular and molecular level has not been considered. We report here an investigation of water diffusion through erythrocyte membranes in epileptic children, made using a nuclear magnetic resonance (NMR) technique7. We found an abnormally low permeability in membranes from epileptics and suggest that a generalised membrane defect affecting water permeability is responsible for the disturbances of water metabolism in human epilepsy.

Effect of Picloram on Germination and Seedling Development of Four Species

Laboratory and greenhouse studies were conducted to determine the response of four plant species to 4-amino-3,5,6-trichloropicolinic acid (picloram). Germination of soybean (Glycine max(L.) Merr., var. Lee) seeds was inhibited, step-wise, by 10−8to 10−3M concentrations of picloram. Safflower (Carthamus tinctoriusL.) germination was inhibited at 10−3M; however, radish (Raphanus sativusL.) and barley (Hordeum vulgareL.) were not affected by any concentration studied (10−6to 10−3M). Measurement of several parameters of growth such as fresh and dry weight, shoot height, number and dimensions of leaves, percent necrosis, hypocotyl or epicotyl length, and hypocotyl diameter revealed that picloram was both growth promotive and inhibitory to safflower, radish, and barley. Levels of picloram required for growth promotion or inhibition varied with the species, stage of plant growth, herbicide concentration, the specific tissue, and the parameter being measured. Typical malformations such as twisting of stems, death of growing points, and occurrence of callus growth (depending on the species and herbicide dosage) were observed in picloram-treated seedlings. Studies on water loss by evapotranspiration suggested that picloram caused a possible alteration of stomatal behavior and/or a disturbance of water metabolism in plants under appropriate conditions.