Brief Answer: Yes , it can cause. However , not very common Detailed Answer: Dear Sir Welcome to XXXXXXX I am Dr Anshul Varshney . I have read your query in detail. I understand your concern. Beta Blockers like Metoprolol can cause reduction in Sodium levels (Hyponatremia). It is not a frequent side effect of Metoprolol , but it is not unseen. It can occur. The reason if you wish to know is that Beta blockade, especially of the beta-1 receptor at the macula densa, inhibits renin release, thus decreasing the release of aldosterone. This causes hyponatremia and hyperkalemia. However , mostly increase frequency of micturation and hyponatremia are caused by another class of Anti Hypertensives known as Diuretic. Just check if you are on diuretics like Frusemide , Torsemide , Hydrochlorothiazide. If you have associated hesitancy , urgency of micturation with poor stream , you might be having a Prostate Hyperplasia. Get Evaluated if you have these symptoms. This is my best advice for you based on details available here. If you have any further query, you may please ask me. Stay Healthy. Dr Anshul Varshney , MD

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