Hypokalemia with syncope caused by habitual drinking of oolong tea

Caffeine-induced hypokalemia: a case report

Background

With an increase in the global popularity of coffee, caffeine is one of the most consumed ingredients of modern times. However, the consumption of massive amounts of caffeine can lead to severe hypokalemia.

Case presentation

A 29-year-old man without a specific past medical history was admitted to our hospital with recurrent episodes of sudden and severe lower-extremity weakness. Laboratory tests revealed low serum potassium concentration (2.6–2.9 mmol/L) and low urine osmolality (100–130 mOsm/kgH₂O) in three such prior episodes. Urinary potassium/urinary creatinine ratio was 12 and 16 mmol/gCr, respectively. The patient was not under medication with laxatives, diuretics, or herbal remedies. Through an in-depth interview, we found that the patient consumed large amounts of caffeine-containing beverages daily, which included > 15 cups of coffee, soda, and various kinds of tea. After the cessation of coffee intake and concomitant intravenous potassium replacement, the symptoms rapidly resolved, and the serum potassium level normalized.

Conclusions

An increased intracellular shift of potassium and increased loss of potassium in urine due to the diuretic action have been suggested to be the causes of caffeine-induced hypokalemia. In cases of recurring hypokalemia of unknown cause, high caffeine intake should be considered.

Oolong tea: A critical review of processing methods, chemical composition, health effects, and risk

Oolong tea (OT) is a traditional Chinese tea (Camellia sinensis) and is especially popular in south China. This review is to comprehensively summarize the miscellaneous research that has been done towards to the processing, phytochemistry, health benefit, and risk of OT. These literatures were carried out not only from different electronic databases but also from text books written in English, Japanese, and Chinese, including those traditional records tracing back to the Tang Dynasty (A.D. 618-907). The full process OT producing is depicted below in this review. The phytochemistry of OT has been comprehensively investigated. More than 100 chemical compositions have been isolated and identified. In health benefit, OT performs outstandingly in reducing obesity and controlling diabetes explained by modern pharmacological studies. (-)-Epigallocatechin-3-gallate (6) in OT prevention of cancerous cells developing. OT can also improve and reduce on heart and vascular disease, protect teeth and bone, function as anti-oxidative and antibacterial agents. This review also mentioned the risk, summarized briefly on various forms of toxicity and harmful associated with OT. In short, this review can provided a natural product library of OT, gave inspirations for further new garden systems, designed idea on quality, bioactivity-oriented screening. In addition, it is suggested more scientists and education is necessary to guarantee the stability and safety of drinking OT.

Heart rate, blood pressure and repolarization effects of an energy drink as compared to coffee

The goal of this study was to investigate the impact of energy drinks on haemodynamic and cardiac physiology. Comparisons were made to coffee as well as water consumption. In Protocol #1 the caffeine content was normalized to body weight to represent a controlled environment. Heart rate, blood pressure and cardiac QTc interval were assessed in 15 participants, on 4 days, prior to and for 6·5 h postconsumption of (i) energy drink (2 mg caffeine per kg body weight; low dose), (ii) energy drink (3 mg caffeine per kg body weight; medium dose), (iii) coffee (2 mg caffeine per kg body weight) and (iv) 250 ml water. In Protocol #2, the beverages were consumed in volumes that they are purchased to represent real-life conditions. The aforementioned measurements were repeated in 15 participants following (i) 1 16 oz can of energy drink (16 oz Monster), (ii) 1 24 oz can of energy drink (24 oz Monster), (iii) 1 packet of Keurig K-Cup Starbucks coffee (coffee) and (iv) 250 ml water. The order of the beverages was performed in a randomized double-blinded fashion. For both protocols, QTc interval, heart rate and systolic blood pressure were unchanged in any condition (P>0·05). Diastolic blood pressure and mean blood pressure were slightly elevated in Protocol #1 (P<0·05, main effect of time) with no difference between beverages (P<0·05, interaction of beverage × time); however, they were unaffected in Protocol #2 (P>0·05). These findings suggest that acute consumption of these commonly consumed beverages has no negative effect on cardiac QTc interval.

Coffee-induced Hypokalaemia

Taking an excess amount of caffeine (e.g. overdrinking caffeinated beverages) sometimes causes hypokalaemia. Although the detailed mechanism has not been clarified yet, an increased loss of potassium via the urine stream caused by the diuretic action of caffeine is proposed as one of the possibilities. We report the case of a 50-year-old female outpatient who rapidly developed severe generalized muscle weakness and fatigue. Her symptoms were considered to be principally due to hypokalaemia. Since her blood urea nitrogen concentration decreased greatly, it was suggested that she had massive polyuria due to overhydration (i.e. dilution of her body fluids). Initially, we considered that a urinary tract infection might have caused her illness. However, we found that she was a heavy coffee drinker and had constantly experienced massive diuresis. After a course of oral antibiotics, potassium replacement and stopping coffee (caffeine) ingestion, her symptoms resolved quickly. In conclusion, it was considered that overdrinking coffee (caffeine) induced her hypokalaemia. Probably, loss of potassium via the urine stream with secondary aldosteronism was the main cause of the hypokalaemia.

Cola-induced hypokalaemia: pathophysiological mechanisms and clinical implications

BACKGROUND/AIMS

The consumption of soft drinks has increased considerably during the last decades. Among them, the cola-based preparations are possibly the refreshments with the largest sales worldwide. In addition to the possible detrimental effects of moderate, chronic cola consumption, it has been proposed that the consumption of large amounts of cola-based soft drinks may result in severe hypokalaemia.

METHODS

In this review, we discuss the clinical significance of these disturbances and summarise the pathophysiological mechanism that may underlie the development of this rare, but potentially severe, side effect.

RESULTS/CONCLUSION

Several lines of evidence suggest that the chronic consumption of large amounts of cola soft drinks may adversely affect potassium homeostasis and result in potentially severe conditions such as hypokalaemic myopathy.

Evaluation of electrocardiographic and hemodynamic effects of caffeine with acute dosing in healthy volunteers

STUDY OBJECTIVE

To evaluate the effects of moderate, single-dose caffeine consumption on electrocardiographic variables: PR, QRS, QT, QTc, and RR intervals, and QT and QTc interval dispersion. Effects of caffeine on blood pressure and heart rate also were evaluated.

DESIGN

Randomized, double-blind, placebo-controlled, crossover study.

SETTING

University school of pharmacy.

PATIENTS

Ten healthy volunteers aged 17 years or older.

INTERVENTION

Participants abstained from caffeinated products for at least 2 days before the study began and were randomly designated to receive placebo or caffeine 400 mg on various days. For each of the study phases, a baseline 12-lead electrocardiogram (ECG) was performed and a subsequent 12-lead ECG performed 3 hours after ingesting the study drug. Blood pressure readings were taken with each ECG.

MEASUREMENTS AND MAIN RESULTS

No significant changes in any intragroup or intergroup electrocardiographic variables occurred. Caffeine increased blood pressure (systolic blood pressure [SBP]/diastolic blood pressure [DBP]) from 118+/-5/75+/-6 mm Hg to 128+/-8/77+/-7 mm Hg versus baseline (p=0.0022 and p=0.0368 for SBP and DBP, respectively). After drug dosing, SBP in the caffeine group was significantly higher than in the placebo group (128+/-8 mm Hg versus 119+/-7 mm Hg, p=0.0174).

CONCLUSION

Moderate caffeine consumption by healthy young adults does not acutely affect PR, QRS, QT, QTc, and RR intervals, or QT and QTc interval dispersion. Caffeine-naive subjects experienced persistent elevations in SBP and DBP 3 hours after caffeine ingestion, indicating that longer caffeine abstinence than that which is recommended is necessary for blood pressure determination in the clinical setting.