Antigens after COVID not infectious
Dear Dr. Roach: Will I continue to test positive for COVID-19 antigens even after I recover from the virus? Once you have the antigens in your system, don’t they stay there for a while?
R.L.M.
Answer: It is frequent that people will have persistently positive COVID-19 tests after infection, sometimes for weeks, but that does not mean that they are still infectious. It is quite rare for a person with a normal immune system and mild or moderate disease to continue to be infectious more than 10 days after the onset of infection. People who have had severe disease or those with severe immune system disease may continue to be infectious 20 or more days after infection and should consult an expert for information on duration of isolation.
Dear Dr. Roach: I have low sodium levels running between 128 and 131 mEq/L for several years. I was on hydrochlorothiazide for many years, but I was taken off some time ago. My sodium remained low. I don’t feel like I drink an excess of water. Should I be concerned?
Answer: A normal sodium level in the blood
S.H. is between 135 and 145 mEq/L. You have a slightly low sodium level, which is common. There are many different causes. Diuretics are a common one. One condition that physicians are frequently concerned about is the syndrome of inappropriate anti-diuretic hormone secretion. In this condition (SIADH), a hormone called antidiuretic hormone is secreted all the time, causing the urine to be too concentrated and the sodium level to be too high. The problem is really about water, not salt; therefore, water restriction is the primary treatment.
The brain has an area responsible for maintaining sodium levels (called the “osmostat”). One possibility is that the years you spent on hydrochlorothiazide “reset” your osmostat to this slightly lower sodium level.
You should talk to your regular doctor about whether you need treatment and whether some moderate fluid restriction is the right treatment for you. A kidney specialist is the expert in diagnosis and management of SIADH and a reset for the osmostat.