While there has been speculation about a connection between early-onset male pattern hair loss and heart disease, a review of articles from 1954 to 1999 found no conclusive connection between baldness and coronary artery disease. The dermatologists who conducted the review suggested further study was needed.Environmental factors are under review. A 2007 study indicated that smoking may be a factor associated with age-related hair loss among Asian men. The study controlled for age and family history, and found statistically significant positive associations between moderate or severe male pattern hair loss and smoking status.Vertex baldness is associated with an increased risk of coronary heart disease (CHD) and the relationship depends upon the severity of baldness, while frontal baldness is not. Thus, vertex baldness might be a marker of CHD and is more closely associated with atherosclerosis than frontal baldness. Hair follicle aging
A key aspect of hair loss with age is the aging of the hair follicle. Ordinarily, hair follicle renewal is maintained by the stem cells associated with each follicle. Aging of the hair follicle appears to be primed by a sustained cellular response to the DNA damage that accumulates in renewing stem cells during aging. This damage response involves the proteolysis of type XVII collagen by neutrophil elastase in response to DNA damage in hair follicle stem cells. Proteolysis of collagen leads to elimination of the damaged cells and,  consequently, to terminal hair follicle miniaturization.
It is important to recognize nitrofurantoin as possible cause of symptoms and discontinue the drug when the suspicion of pulmonary side effects arises as it can be reversible if the drug is stopped early. Liver toxicity
Hepatic reactions, including hepatitis, cholestatic jaundice, chronic active hepatitis, and hepatic necrosis, occur rarely. The onset of chronic active hepatitis may be insidious, and patients should be monitored periodically for changes in biochemical tests that would indicate liver injury. These reactions usually occur after exposure to the drug for more than 6 weeks. If signs of liver failure are observed in a patient taking nitrofurantoin, the drug should be discontinued. Re-challenge with the drug at a later date is not recommended, as the reaction may have a hypersensitivity component and recur when the drug is resumed. Neuropathy
Neuropathy is a rare side effect of taking nitrofurantoin. Patients may experience numbness and tingling in a stocking-glove pattern, which may or may not improve upon discontinuation of the drug. Pharmacology
Organisms are said to be susceptible to nitrofurantoin if their minimum inhibitory concentration is 32 μg/mL or less. The peak blood concentration of nitrofurantoin following an oral dose of nitrofurantoin 100 mg is less than 1 μg/mL and may be undetectable. Its bioavailability is about 90% and the urinary excretion is 40% tissue penetration is negligible; the drug is well concentrated in the urine: 75% of the dose is rapidly metabolised by the liver, but 25% of the dose is excreted in the urine unchanged, reliably achieving levels of 200 μg/mL or more.