DEAR DR. DONOHUE: I am totally familiar with the consequences of high blood pressure, but I have learned nothing about low blood pressure. Please help. -- C.S.
ANSWER: Normal blood pressure has been set at less than 120 over 80. People who have lower pressures actually appear to lead longer lives. A systolic pressure (first number) below 90 (some say 80) and a diastolic pressure (second number) much lower than 60 are the usual cutoffs for low blood pressure. Some people have readings lower than these numbers but have no symptoms. Those people are not affected by their readings.
On the other hand, most people with lower readings feel tired all the time or on the verge of passing out. Symptomatic low blood pressure requires treatment. The brain suffers, as do other organs, if pressure is too low to support their nourishment by circulating adequate amounts of blood.
When large volumes of blood are lost, when blood vessels dilate and pool blood, or when people are depleted of fluid, blood pressure falls so low that people lapse into a coma. That state is called shock.
Older people sometimes have to deal with trouble in maintaining blood pressure when they rise from the seated or lying positions. For a healthy person, that change in posture is taken care of by reflexes that keep blood pressure up when one suddenly stands. For older people whose reflexes are not functioning well, blood pressure drops, and they feel like they are about to pass out. This is called orthostatic (standing upright) hypotension (low blood pressure).
DEAR DR. DONOHUE: My 52-year-old husband had a radical prostatectomy due to prostate cancer. Unfortunately, they had to remove nerves that enable an erection.
While I am so happy that his life has been saved, I am utterly and completely heartbroken at the demise of our intimate life, which had been so important to us. Will you explain how penile implants work? -- R.M.
ANSWER: One type of implant is a malleable, semirigid rod implanted in the penis. The rod can be bent to a horizontal position for intercourse. It's a reliable device with a long life.
Another, more complicated device consists of a small pump placed in the scrotum. A reservoir containing saline (saltwater) is put in the lower abdomen. The reservoir is connected to two soft cylinders that are positioned in the penis. A release button causes the inflow of saline into the cylinders, which produces an erection.
Your husband also could try an instrument that creates a vacuum to draw blood into the penis. A ring is then placed around the base of the penis to keep blood in the organ.
You and your husband ought to discuss the possibilities with his urologist. It would be best if the doctor had examples of these devices to show you.
DEAR DR. DONOHUE: I have osteoporosis and have taken Fosamax for more than 10 years. I was advised to stop it two years ago. My bone density showed a decline, and the doctor suggested Prolia. The cost is about $900 for each of two yearly injections. It's probably not covered by insurance. What is your opinion of Prolia? -- B.S.
ANSWER: Prolia is the newest osteoporosis drug. It works by inhibiting bone cells that lead to bone destruction. That allows bone cells that build up bone to have a larger impact. Check to see if the drug is covered by insurance. If it is, then I'd go for it. If it's not, I'd think of other options, like Evista, calcitonin or Forteo.
Don't forget daily calcium (1,000 to 1,200 mg daily) and vitamin D (600 to 800 IU a day). Exercise is most important. Walking qualifies as bone-building.